Add a listener for changing a property value

canvasView.go

@@ -53,6 +53,7 @@ func (canvasView *canvasViewData) remove(tag string) {
 	if tag == DrawFunction {
 		canvasView.drawer = nil
 		canvasView.Redraw()
+		canvasView.propertyChangedEvent(tag)
 	} else {
 		canvasView.viewData.remove(tag)
 	}
@@ -73,6 +74,7 @@ func (canvasView *canvasViewData) set(tag string, value interface{}) bool {
 			return false
 		}
 		canvasView.Redraw()
+		canvasView.propertyChangedEvent(tag)
 		return true
 	}
 

checkbox.go

@@ -57,13 +57,16 @@ func (button *checkboxData) Get(tag string) interface{} {
 }
 
 func (button *checkboxData) Set(tag string, value interface{}) bool {
-	switch strings.ToLower(tag) {
+	return button.set(tag, value)
+}
+
+func (button *checkboxData) set(tag string, value interface{}) bool {
+	switch tag {
 	case CheckboxChangedEvent:
-		ok := button.setChangedListener(value)
+		if !button.setChangedListener(value) {
-		if !ok {
 			notCompatibleType(tag, value)
+			return false
 		}
-		return ok
 
 	case Checked:
 		oldChecked := button.checked()
@@ -76,46 +79,60 @@ func (button *checkboxData) Set(tag string, value interface{}) bool {
 				button.changedCheckboxState(checked)
 			}
 		}
-		return true
 
 	case CheckboxHorizontalAlign, CheckboxVerticalAlign:
-		if button.setEnumProperty(tag, value, enumProperties[tag].values) {
+		if !button.setEnumProperty(tag, value, enumProperties[tag].values) {
+			return false
+		}
 		if button.created {
 			htmlID := button.htmlID()
 			updateCSSStyle(htmlID, button.session)
 			updateInnerHTML(htmlID, button.session)
 		}
-			return true
-		}
-		return false
 
 	case VerticalAlign:
-		if button.setEnumProperty(tag, value, enumProperties[tag].values) {
+		if !button.setEnumProperty(tag, value, enumProperties[tag].values) {
+			return false
+		}
 		if button.created {
 			updateCSSProperty(button.htmlID()+"content", "align-items", button.cssVerticalAlign(), button.session)
 		}
-			return true
-		}
-		return false
 
 	case HorizontalAlign:
-		if button.setEnumProperty(tag, value, enumProperties[tag].values) {
+		if !button.setEnumProperty(tag, value, enumProperties[tag].values) {
+			return false
+		}
 		if button.created {
 			updateCSSProperty(button.htmlID()+"content", "justify-items", button.cssHorizontalAlign(), button.session)
 		}
-			return true
-		}
-		return false
 
 	case CellVerticalAlign, CellHorizontalAlign, CellWidth, CellHeight:
 		return false
+
+	default:
+		return button.viewsContainerData.set(tag, value)
 	}
 
-	return button.viewsContainerData.Set(tag, value)
+	button.propertyChangedEvent(tag)
+	return true
 }
 
 func (button *checkboxData) Remove(tag string) {
-	switch strings.ToLower(tag) {
+	button.remove(strings.ToLower(tag))
+}
+
+func (button *checkboxData) remove(tag string) {
+	switch tag {
+	case ClickEvent:
+		if !button.viewsContainerData.set(ClickEvent, checkboxClickListener) {
+			delete(button.properties, tag)
+		}
+
+	case KeyDownEvent:
+		if !button.viewsContainerData.set(KeyDownEvent, checkboxKeyListener) {
+			delete(button.properties, tag)
+		}
+
 	case CheckboxChangedEvent:
 		if len(button.checkedListeners) > 0 {
 			button.checkedListeners = []func(Checkbox, bool){}
@@ -124,27 +141,35 @@ func (button *checkboxData) Remove(tag string) {
 	case Checked:
 		oldChecked := button.checked()
 		delete(button.properties, tag)
-		if oldChecked {
+		if button.created && oldChecked {
 			button.changedCheckboxState(false)
 		}
 
 	case CheckboxHorizontalAlign, CheckboxVerticalAlign:
 		delete(button.properties, tag)
+		if button.created {
 			htmlID := button.htmlID()
 			updateCSSStyle(htmlID, button.session)
 			updateInnerHTML(htmlID, button.session)
+		}
 
 	case VerticalAlign:
 		delete(button.properties, tag)
+		if button.created {
 			updateCSSProperty(button.htmlID()+"content", "align-items", button.cssVerticalAlign(), button.session)
+		}
 
 	case HorizontalAlign:
 		delete(button.properties, tag)
+		if button.created {
 			updateCSSProperty(button.htmlID()+"content", "justify-items", button.cssHorizontalAlign(), button.session)
+		}
 
 	default:
-		button.viewsContainerData.Remove(tag)
+		button.viewsContainerData.remove(tag)
+		return
 	}
+	button.propertyChangedEvent(tag)
 }
 
 func (button *checkboxData) checked() bool {

colorPicker.go

@@ -56,7 +56,10 @@ func (picker *colorPickerData) Remove(tag string) {
 func (picker *colorPickerData) remove(tag string) {
 	switch tag {
 	case ColorChangedEvent:
+		if len(picker.colorChangedListeners) > 0 {
 			picker.colorChangedListeners = []func(ColorPicker, Color){}
+			picker.propertyChangedEvent(tag)
+		}
 
 	case ColorPickerValue:
 		oldColor := GetColorPickerValue(picker, "")
@@ -131,15 +134,13 @@ func (picker *colorPickerData) set(tag string, value interface{}) bool {
 			}
 			picker.colorChangedListeners = listeners
 		}
+		picker.propertyChangedEvent(tag)
 		return true
 
 	case ColorPickerValue:
 		oldColor := GetColorPickerValue(picker, "")
 		if picker.setColorProperty(ColorPickerValue, value) {
-			newValue := GetColorPickerValue(picker, "")
-			if oldColor != newValue {
 			picker.colorChanged(oldColor)
-			}
 			return true
 		}
 
@@ -150,12 +151,14 @@ func (picker *colorPickerData) set(tag string, value interface{}) bool {
 }
 
 func (picker *colorPickerData) colorChanged(oldColor Color) {
-	newColor := GetColorPickerValue(picker, "")
+	if newColor := GetColorPickerValue(picker, ""); oldColor != newColor {
-	if oldColor != newColor {
+		if picker.created {
 			picker.session.runScript(fmt.Sprintf(`setInputValue('%s', '%s')`, picker.htmlID(), newColor.rgbString()))
+		}
 		for _, listener := range picker.colorChangedListeners {
 			listener(picker, newColor)
 		}
+		picker.propertyChangedEvent(ColorTag)
 	}
 }
 
@@ -188,7 +191,7 @@ func (picker *colorPickerData) htmlProperties(self View, buffer *strings.Builder
 }
 
 func (picker *colorPickerData) htmlDisabledProperties(self View, buffer *strings.Builder) {
-	if IsDisabled(self) {
+	if IsDisabled(self, "") {
 		buffer.WriteString(` disabled`)
 	}
 	picker.viewData.htmlDisabledProperties(self, buffer)

columnLayout.go

@@ -82,6 +82,7 @@ func (columnLayout *columnLayoutData) Remove(tag string) {
 
 func (columnLayout *columnLayoutData) remove(tag string) {
 	columnLayout.viewsContainerData.remove(tag)
+	if columnLayout.created {
 		switch tag {
 		case ColumnCount, ColumnWidth, ColumnGap:
 			updateCSSProperty(columnLayout.htmlID(), tag, "", columnLayout.Session())
@@ -89,6 +90,7 @@ func (columnLayout *columnLayoutData) remove(tag string) {
 		case ColumnSeparator:
 			updateCSSProperty(columnLayout.htmlID(), "column-rule", "", columnLayout.Session())
 		}
+	}
 }
 
 func (columnLayout *columnLayoutData) Set(tag string, value interface{}) bool {
@@ -101,22 +103,11 @@ func (columnLayout *columnLayoutData) set(tag string, value interface{}) bool {
 		return true
 	}
 
-	switch tag {
+	if !columnLayout.viewsContainerData.set(tag, value) {
-	case ColumnCount:
-		if columnLayout.setIntProperty(tag, value) {
-			session := columnLayout.Session()
-			if count, ok := intProperty(columnLayout, tag, session, 0); ok && count > 0 {
-				updateCSSProperty(columnLayout.htmlID(), tag, strconv.Itoa(count), session)
-			} else {
-				updateCSSProperty(columnLayout.htmlID(), tag, "auto", session)
-			}
-			return true
-		}
 		return false
 	}
 
-	ok := columnLayout.viewsContainerData.set(tag, value)
+	if columnLayout.created {
-	if ok {
 		switch tag {
 		case ColumnSeparator:
 			css := ""
@@ -126,9 +117,17 @@ func (columnLayout *columnLayoutData) set(tag string, value interface{}) bool {
 				css = separator.cssValue(columnLayout.Session())
 			}
 			updateCSSProperty(columnLayout.htmlID(), "column-rule", css, session)
+
+		case ColumnCount:
+			session := columnLayout.Session()
+			if count, ok := intProperty(columnLayout, tag, session, 0); ok && count > 0 {
+				updateCSSProperty(columnLayout.htmlID(), tag, strconv.Itoa(count), session)
+			} else {
+				updateCSSProperty(columnLayout.htmlID(), tag, "auto", session)
 			}
 		}
-	return ok
+	}
+	return true
 }
 
 // GetColumnCount returns int value which specifies number of columns into which the content of

customView.go

@@ -68,6 +68,10 @@ func (customView *CustomViewData) SetAnimated(tag string, value interface{}, ani
 	return customView.superView.SetAnimated(tag, value, animation)
 }
 
+func (customView *CustomViewData) SetChangeListener(tag string, listener func(View, string)) {
+	customView.superView.SetChangeListener(tag, listener)
+}
+
 // Remove removes the property with name defined by the argument
 func (customView *CustomViewData) Remove(tag string) {
 	customView.superView.Remove(tag)

datePicker.go

@@ -63,28 +63,47 @@ func (picker *datePickerData) remove(tag string) {
 	case DateChangedEvent:
 		if len(picker.dateChangedListeners) > 0 {
 			picker.dateChangedListeners = []func(DatePicker, time.Time){}
+			picker.propertyChangedEvent(tag)
 		}
+		return
 
 	case DatePickerMin:
 		delete(picker.properties, DatePickerMin)
+		if picker.created {
 			removeProperty(picker.htmlID(), Min, picker.session)
+		}
 
 	case DatePickerMax:
 		delete(picker.properties, DatePickerMax)
+		if picker.created {
 			removeProperty(picker.htmlID(), Max, picker.session)
+		}
 
 	case DatePickerStep:
 		delete(picker.properties, DatePickerMax)
+		if picker.created {
 			removeProperty(picker.htmlID(), Step, picker.session)
+		}
 
 	case DatePickerValue:
+		if _, ok := picker.properties[DatePickerValue]; ok {
 			delete(picker.properties, DatePickerValue)
-		updateProperty(picker.htmlID(), Value, time.Now().Format(dateFormat), picker.session)
+			date := GetDatePickerValue(picker, "")
+			if picker.created {
+				picker.session.runScript(fmt.Sprintf(`setInputValue('%s', '%s')`, picker.htmlID(), date.Format(dateFormat)))
+			}
+			for _, listener := range picker.dateChangedListeners {
+				listener(picker, date)
+			}
+		} else {
+			return
+		}
 
 	default:
 		picker.viewData.remove(tag)
-		picker.propertyChanged(tag)
+		return
 	}
+	picker.propertyChangedEvent(tag)
 }
 
 func (picker *datePickerData) Set(tag string, value interface{}) bool {
@@ -98,7 +117,6 @@ func (picker *datePickerData) set(tag string, value interface{}) bool {
 	}
 
 	setTimeValue := func(tag string) (time.Time, bool) {
-		//old, oldOK := getDateProperty(picker, tag, shortTag)
 		switch value := value.(type) {
 		case time.Time:
 			picker.properties[tag] = value
@@ -122,8 +140,11 @@ func (picker *datePickerData) set(tag string, value interface{}) bool {
 		old, oldOK := getDateProperty(picker, DatePickerMin, Min)
 		if date, ok := setTimeValue(DatePickerMin); ok {
 			if !oldOK || date != old {
+				if picker.created {
 					updateProperty(picker.htmlID(), Min, date.Format(dateFormat), picker.session)
 				}
+				picker.propertyChangedEvent(tag)
+			}
 			return true
 		}
 
@@ -131,33 +152,41 @@ func (picker *datePickerData) set(tag string, value interface{}) bool {
 		old, oldOK := getDateProperty(picker, DatePickerMax, Max)
 		if date, ok := setTimeValue(DatePickerMax); ok {
 			if !oldOK || date != old {
+				if picker.created {
 					updateProperty(picker.htmlID(), Max, date.Format(dateFormat), picker.session)
 				}
+				picker.propertyChangedEvent(tag)
+			}
 			return true
 		}
 
 	case DatePickerStep:
 		oldStep := GetDatePickerStep(picker, "")
 		if picker.setIntProperty(DatePickerStep, value) {
-			step := GetDatePickerStep(picker, "")
+			if step := GetDatePickerStep(picker, ""); oldStep != step {
-			if oldStep != step {
+				if picker.created {
 					if step > 0 {
 						updateProperty(picker.htmlID(), Step, strconv.Itoa(step), picker.session)
 					} else {
 						removeProperty(picker.htmlID(), Step, picker.session)
 					}
 				}
+				picker.propertyChangedEvent(tag)
+			}
 			return true
 		}
 
 	case DatePickerValue:
 		oldDate := GetDatePickerValue(picker, "")
 		if date, ok := setTimeValue(DatePickerMax); ok {
-			picker.session.runScript(fmt.Sprintf(`setInputValue('%s', '%s')`, picker.htmlID(), date.Format(dateFormat)))
 			if date != oldDate {
+				if picker.created {
+					picker.session.runScript(fmt.Sprintf(`setInputValue('%s', '%s')`, picker.htmlID(), date.Format(dateFormat)))
+				}
 				for _, listener := range picker.dateChangedListeners {
 					listener(picker, date)
 				}
+				picker.propertyChangedEvent(tag)
 			}
 			return true
 		}
@@ -214,13 +243,11 @@ func (picker *datePickerData) set(tag string, value interface{}) bool {
 			}
 			picker.dateChangedListeners = listeners
 		}
+		picker.propertyChangedEvent(tag)
 		return true
 
 	default:
-		if picker.viewData.set(tag, value) {
+		return picker.viewData.set(tag, value)
-			picker.propertyChanged(tag)
-			return true
-		}
 	}
 	return false
 }
@@ -274,7 +301,7 @@ func (picker *datePickerData) htmlProperties(self View, buffer *strings.Builder)
 }
 
 func (picker *datePickerData) htmlDisabledProperties(self View, buffer *strings.Builder) {
-	if IsDisabled(self) {
+	if IsDisabled(self, "") {
 		buffer.WriteString(` disabled`)
 	}
 	picker.viewData.htmlDisabledProperties(self, buffer)

demo/textStyle.go

@@ -57,6 +57,15 @@ func createTextStyleDemo(session rui.Session) rui.View {
 		return nil
 	}
 
+	rui.SetChangeListener(view, "textStyleFont", rui.Current, func(v rui.View, tag string) {
+		fonts := []string{"", "serif", "sans-serif", "\"Courier new\", monospace", "cursive", "fantasy"}
+		if number := rui.GetDropDownCurrent(v, ""); number > 0 && number < len(fonts) {
+			rui.Set(view, "textStyleText", rui.FontName, fonts[number])
+		} else {
+			rui.Set(view, "textStyleText", rui.FontName, nil)
+		}
+	})
+	/*
 		rui.Set(view, "textStyleFont", rui.DropDownEvent, func(number int) {
 			fonts := []string{"", "serif", "sans-serif", "\"Courier new\", monospace", "cursive", "fantasy"}
 			if number > 0 && number < len(fonts) {
@@ -65,6 +74,7 @@ func createTextStyleDemo(session rui.Session) rui.View {
 				rui.Set(view, "textStyleText", rui.FontName, nil)
 			}
 		})
+	*/
 
 	rui.Set(view, "textStyleSize", rui.DropDownEvent, func(number int) {
 		sizes := []string{"1em", "14pt", "12px", "1.5em"}

detailsView.go

@@ -2,6 +2,8 @@ package rui
 
 import "strings"
 
+// TODO Expanded event
+
 const (
 	// Summary is the constant for the "summary" property tag.
 	// The contents of the "summary" property are used as the label for the disclosure widget.
@@ -45,18 +47,14 @@ func (detailsView *detailsViewData) Remove(tag string) {
 }
 
 func (detailsView *detailsViewData) remove(tag string) {
-	if _, ok := detailsView.properties[tag]; ok {
+	detailsView.viewsContainerData.remove(tag)
+	if detailsView.created {
 		switch tag {
 		case Summary:
-			delete(detailsView.properties, tag)
 			updateInnerHTML(detailsView.htmlID(), detailsView.Session())
 
 		case Expanded:
-			delete(detailsView.properties, tag)
 			removeProperty(detailsView.htmlID(), "open", detailsView.Session())
-
-		default:
-			detailsView.viewsContainerData.remove(tag)
 		}
 	}
 }
@@ -66,6 +64,11 @@ func (detailsView *detailsViewData) Set(tag string, value interface{}) bool {
 }
 
 func (detailsView *detailsViewData) set(tag string, value interface{}) bool {
+	if value == nil {
+		detailsView.remove(tag)
+		return true
+	}
+
 	switch tag {
 	case Summary:
 		switch value := value.(type) {
@@ -86,23 +89,29 @@ func (detailsView *detailsViewData) set(tag string, value interface{}) bool {
 			notCompatibleType(tag, value)
 			return false
 		}
+		if detailsView.created {
 			updateInnerHTML(detailsView.htmlID(), detailsView.Session())
-		return true
+		}
 
 	case Expanded:
-		if detailsView.setBoolProperty(tag, value) {
+		if !detailsView.setBoolProperty(tag, value) {
+			notCompatibleType(tag, value)
+			return false
+		}
+		if detailsView.created {
 			if IsDetailsExpanded(detailsView, "") {
 				updateProperty(detailsView.htmlID(), "open", "", detailsView.Session())
 			} else {
 				removeProperty(detailsView.htmlID(), "open", detailsView.Session())
 			}
-			return true
-		}
-		notCompatibleType(tag, value)
-		return false
 		}
 
+	default:
 		return detailsView.viewsContainerData.Set(tag, value)
+	}
+
+	detailsView.propertyChangedEvent(tag)
+	return true
 }
 
 func (detailsView *detailsViewData) Get(tag string) interface{} {

dropDownList.go

@@ -48,19 +48,31 @@ func (list *dropDownListData) remove(tag string) {
 	case Items:
 		if len(list.items) > 0 {
 			list.items = []string{}
+			if list.created {
 				updateInnerHTML(list.htmlID(), list.session)
 			}
-
+			list.propertyChangedEvent(tag)
-	case Current:
+		}
-		list.set(Current, 0)
 
 	case DropDownEvent:
 		if len(list.dropDownListener) > 0 {
 			list.dropDownListener = []func(DropDownList, int){}
+			list.propertyChangedEvent(tag)
+		}
+
+	case Current:
+		oldCurrent := GetDropDownCurrent(list, "")
+		delete(list.properties, Current)
+		if oldCurrent != 0 {
+			if list.created {
+				list.session.runScript(fmt.Sprintf(`selectDropDownListItem('%s', %d)`, list.htmlID(), 0))
+			}
+			list.onSelectedItemChanged(0)
 		}
 
 	default:
 		list.viewData.remove(tag)
+		return
 	}
 }
 
@@ -73,23 +85,22 @@ func (list *dropDownListData) set(tag string, value interface{}) bool {
 	case Items:
 		return list.setItems(value)
 
+	case DropDownEvent:
+		return list.setDropDownListener(value)
+
 	case Current:
 		oldCurrent := GetDropDownCurrent(list, "")
 		if !list.setIntProperty(Current, value) {
 			return false
 		}
 
-		if !list.session.ignoreViewUpdates() {
+		if current := GetDropDownCurrent(list, ""); oldCurrent != current {
-			current := GetDropDownCurrent(list, "")
+			if list.created {
-			if oldCurrent != current {
 				list.session.runScript(fmt.Sprintf(`selectDropDownListItem('%s', %d)`, list.htmlID(), current))
+			}
 			list.onSelectedItemChanged(current)
 		}
-		}
 		return true
-
-	case DropDownEvent:
-		return list.setDropDownListener(value)
 	}
 
 	return list.viewData.set(tag, value)
@@ -160,9 +171,11 @@ func (list *dropDownListData) setItems(value interface{}) bool {
 		return false
 	}
 
-	if !list.session.ignoreViewUpdates() {
+	if list.created {
 		updateInnerHTML(list.htmlID(), list.session)
 	}
+
+	list.propertyChangedEvent(Items)
 	return true
 }
 
@@ -170,17 +183,14 @@ func (list *dropDownListData) setDropDownListener(value interface{}) bool {
 	switch value := value.(type) {
 	case func(DropDownList, int):
 		list.dropDownListener = []func(DropDownList, int){value}
-		return true
 
 	case func(int):
 		list.dropDownListener = []func(DropDownList, int){func(list DropDownList, index int) {
 			value(index)
 		}}
-		return true
 
 	case []func(DropDownList, int):
 		list.dropDownListener = value
-		return true
 
 	case []func(int):
 		listeners := make([]func(DropDownList, int), len(value))
@@ -194,7 +204,6 @@ func (list *dropDownListData) setDropDownListener(value interface{}) bool {
 			}
 		}
 		list.dropDownListener = listeners
-		return true
 
 	case []interface{}:
 		listeners := make([]func(DropDownList, int), len(value))
@@ -216,13 +225,16 @@ func (list *dropDownListData) setDropDownListener(value interface{}) bool {
 				notCompatibleType(DropDownEvent, value)
 				return false
 			}
+		}
 		list.dropDownListener = listeners
-		}
-		return true
-	}
 
+	default:
 		notCompatibleType(DropDownEvent, value)
 		return false
+	}
+
+	list.propertyChangedEvent(DropDownEvent)
+	return true
 }
 
 func (list *dropDownListData) Get(tag string) interface{} {
@@ -280,7 +292,7 @@ func (list *dropDownListData) htmlProperties(self View, buffer *strings.Builder)
 
 func (list *dropDownListData) htmlDisabledProperties(self View, buffer *strings.Builder) {
 	list.viewData.htmlDisabledProperties(self, buffer)
-	if IsDisabled(list) {
+	if IsDisabled(list, "") {
 		buffer.WriteString(`disabled`)
 	}
 }
@@ -289,6 +301,7 @@ func (list *dropDownListData) onSelectedItemChanged(number int) {
 	for _, listener := range list.dropDownListener {
 		listener(list, number)
 	}
+	list.propertyChangedEvent(Current)
 }
 
 func (list *dropDownListData) handleCommand(self View, command string, data DataObject) bool {

editView.go

@@ -84,63 +84,98 @@ func (edit *editViewData) Remove(tag string) {
 }
 
 func (edit *editViewData) remove(tag string) {
-	if _, ok := edit.properties[tag]; ok {
+	_, exists := edit.properties[tag]
 	switch tag {
 	case Hint:
+		if exists {
 			delete(edit.properties, Hint)
+			if edit.created {
 				removeProperty(edit.htmlID(), "placeholder", edit.session)
+			}
+			edit.propertyChangedEvent(tag)
+		}
 
 	case MaxLength:
+		if exists {
 			delete(edit.properties, MaxLength)
+			if edit.created {
 				removeProperty(edit.htmlID(), "maxlength", edit.session)
+			}
+			edit.propertyChangedEvent(tag)
+		}
 
 	case ReadOnly, Spellcheck:
+		if exists {
 			delete(edit.properties, tag)
+			if edit.created {
 				updateBoolProperty(edit.htmlID(), tag, false, edit.session)
+			}
+			edit.propertyChangedEvent(tag)
+		}
 
 	case EditTextChangedEvent:
 		if len(edit.textChangeListeners) > 0 {
 			edit.textChangeListeners = []func(EditView, string){}
+			edit.propertyChangedEvent(tag)
 		}
 
 	case Text:
+		if exists {
 			oldText := GetText(edit, "")
 			delete(edit.properties, tag)
 			if oldText != "" {
 				edit.textChanged("")
+				if edit.created {
 					edit.session.runScript(fmt.Sprintf(`setInputValue('%s', '%s')`, edit.htmlID(), ""))
 				}
+			}
+		}
 
 	case EditViewPattern:
+		if exists {
 			oldText := GetEditViewPattern(edit, "")
 			delete(edit.properties, tag)
 			if oldText != "" {
+				if edit.created {
 					removeProperty(edit.htmlID(), Pattern, edit.session)
 				}
+				edit.propertyChangedEvent(tag)
+			}
+		}
 
 	case EditViewType:
+		if exists {
 			oldType := GetEditViewType(edit, "")
 			delete(edit.properties, tag)
 			if oldType != 0 {
+				if edit.created {
 					updateInnerHTML(edit.parentHTMLID(), edit.session)
 				}
+				edit.propertyChangedEvent(tag)
+			}
+		}
 
 	case Wrap:
+		if exists {
 			oldWrap := IsEditViewWrap(edit, "")
 			delete(edit.properties, tag)
 			if GetEditViewType(edit, "") == MultiLineText {
 				if wrap := IsEditViewWrap(edit, ""); wrap != oldWrap {
+					if edit.created {
 						if wrap {
 							updateProperty(edit.htmlID(), "wrap", "soft", edit.session)
 						} else {
 							updateProperty(edit.htmlID(), "wrap", "off", edit.session)
 						}
 					}
+					edit.propertyChangedEvent(tag)
+				}
+			}
 		}
 
 	default:
 		edit.viewData.remove(tag)
-		}
+		return
 	}
 }
 
@@ -161,6 +196,7 @@ func (edit *editViewData) set(tag string, value interface{}) bool {
 			edit.properties[Text] = text
 			if text = GetText(edit, ""); oldText != text {
 				edit.textChanged(text)
+				if edit.created {
 					if GetEditViewType(edit, "") == MultiLineText {
 						updateInnerHTML(edit.htmlID(), edit.Session())
 					} else {
@@ -171,6 +207,7 @@ func (edit *editViewData) set(tag string, value interface{}) bool {
 						edit.session.runScript(fmt.Sprintf(`setInputValue('%s', '%s')`, edit.htmlID(), text))
 					}
 				}
+			}
 			return true
 		}
 		return false
@@ -180,12 +217,15 @@ func (edit *editViewData) set(tag string, value interface{}) bool {
 		if text, ok := value.(string); ok {
 			edit.properties[Hint] = text
 			if text = GetHint(edit, ""); oldText != text {
+				if edit.created {
 					if text != "" {
 						updateProperty(edit.htmlID(), "placeholder", text, edit.session)
 					} else {
 						removeProperty(edit.htmlID(), "placeholder", edit.session)
 					}
 				}
+				edit.propertyChangedEvent(tag)
+			}
 			return true
 		}
 		return false
@@ -194,30 +234,39 @@ func (edit *editViewData) set(tag string, value interface{}) bool {
 		oldMaxLength := GetMaxLength(edit, "")
 		if edit.setIntProperty(MaxLength, value) {
 			if maxLength := GetMaxLength(edit, ""); maxLength != oldMaxLength {
+				if edit.created {
 					if maxLength > 0 {
 						updateProperty(edit.htmlID(), "maxlength", strconv.Itoa(maxLength), edit.session)
 					} else {
 						removeProperty(edit.htmlID(), "maxlength", edit.session)
 					}
 				}
+				edit.propertyChangedEvent(tag)
+			}
 			return true
 		}
 		return false
 
 	case ReadOnly:
 		if edit.setBoolProperty(ReadOnly, value) {
+			if edit.created {
 				if IsReadOnly(edit, "") {
 					updateProperty(edit.htmlID(), ReadOnly, "", edit.session)
 				} else {
 					removeProperty(edit.htmlID(), ReadOnly, edit.session)
 				}
+			}
+			edit.propertyChangedEvent(tag)
 			return true
 		}
 		return false
 
 	case Spellcheck:
 		if edit.setBoolProperty(Spellcheck, value) {
+			if edit.created {
 				updateBoolProperty(edit.htmlID(), Spellcheck, IsSpellcheck(edit, ""), edit.session)
+			}
+			edit.propertyChangedEvent(tag)
 			return true
 		}
 		return false
@@ -227,12 +276,15 @@ func (edit *editViewData) set(tag string, value interface{}) bool {
 		if text, ok := value.(string); ok {
 			edit.properties[Pattern] = text
 			if text = GetEditViewPattern(edit, ""); oldText != text {
+				if edit.created {
 					if text != "" {
 						updateProperty(edit.htmlID(), Pattern, text, edit.session)
 					} else {
 						removeProperty(edit.htmlID(), Pattern, edit.session)
 					}
 				}
+				edit.propertyChangedEvent(tag)
+			}
 			return true
 		}
 		return false
@@ -241,8 +293,11 @@ func (edit *editViewData) set(tag string, value interface{}) bool {
 		oldType := GetEditViewType(edit, "")
 		if edit.setEnumProperty(EditViewType, value, enumProperties[EditViewType].values) {
 			if GetEditViewType(edit, "") != oldType {
+				if edit.created {
 					updateInnerHTML(edit.parentHTMLID(), edit.session)
 				}
+				edit.propertyChangedEvent(tag)
+			}
 			return true
 		}
 		return false
@@ -252,12 +307,15 @@ func (edit *editViewData) set(tag string, value interface{}) bool {
 		if edit.setBoolProperty(Wrap, value) {
 			if GetEditViewType(edit, "") == MultiLineText {
 				if wrap := IsEditViewWrap(edit, ""); wrap != oldWrap {
+					if edit.created {
 						if wrap {
 							updateProperty(edit.htmlID(), "wrap", "soft", edit.session)
 						} else {
 							updateProperty(edit.htmlID(), "wrap", "off", edit.session)
 						}
 					}
+					edit.propertyChangedEvent(tag)
+				}
 			}
 			return true
 		}
@@ -268,6 +326,7 @@ func (edit *editViewData) set(tag string, value interface{}) bool {
 		if !ok {
 			notCompatibleType(tag, value)
 		}
+		edit.propertyChangedEvent(tag)
 		return ok
 	}
 
@@ -363,6 +422,7 @@ func (edit *editViewData) textChanged(newText string) {
 	for _, listener := range edit.textChangeListeners {
 		listener(edit, newText)
 	}
+	edit.propertyChangedEvent(Text)
 }
 
 func (edit *editViewData) htmlTag() string {
@@ -446,7 +506,7 @@ func (edit *editViewData) htmlProperties(self View, buffer *strings.Builder) {
 }
 
 func (edit *editViewData) htmlDisabledProperties(self View, buffer *strings.Builder) {
-	if IsDisabled(self) {
+	if IsDisabled(self, "") {
 		buffer.WriteString(` disabled`)
 	}
 	edit.viewData.htmlDisabledProperties(self, buffer)

filePicker.go

@@ -114,7 +114,17 @@ func (picker *filePickerData) Remove(tag string) {
 func (picker *filePickerData) remove(tag string) {
 	switch tag {
 	case FileSelectedEvent:
+		if len(picker.fileSelectedListeners) > 0 {
 			picker.fileSelectedListeners = []func(FilePicker, []FileInfo){}
+			picker.propertyChangedEvent(tag)
+		}
+
+	case Accept:
+		delete(picker.properties, tag)
+		if picker.created {
+			removeProperty(picker.htmlID(), "accept", picker.Session())
+		}
+		picker.propertyChangedEvent(tag)
 
 	default:
 		picker.viewData.remove(tag)
@@ -184,6 +194,7 @@ func (picker *filePickerData) set(tag string, value interface{}) bool {
 			}
 			picker.fileSelectedListeners = listeners
 		}
+		picker.propertyChangedEvent(tag)
 		return true
 
 	case Accept:
@@ -218,6 +229,15 @@ func (picker *filePickerData) set(tag string, value interface{}) bool {
 			notCompatibleType(tag, value)
 			return false
 		}
+
+		if picker.created {
+			if css := picker.acceptCSS(); css != "" {
+				updateProperty(picker.htmlID(), "accept", css, picker.Session())
+			} else {
+				removeProperty(picker.htmlID(), "accept", picker.Session())
+			}
+		}
+		picker.propertyChangedEvent(tag)
 		return true
 
 	default:
@@ -271,7 +291,7 @@ func (picker *filePickerData) htmlProperties(self View, buffer *strings.Builder)
 }
 
 func (picker *filePickerData) htmlDisabledProperties(self View, buffer *strings.Builder) {
-	if IsDisabled(self) {
+	if IsDisabled(self, "") {
 		buffer.WriteString(` disabled`)
 	}
 	picker.viewData.htmlDisabledProperties(self, buffer)

gridLayout.go

@@ -216,10 +216,12 @@ func (gridLayout *gridLayoutData) remove(tag string) {
 	if tag == Gap {
 		gridLayout.remove(GridRowGap)
 		gridLayout.remove(GridColumnGap)
+		gridLayout.propertyChangedEvent(Gap)
 		return
 	}
 
 	gridLayout.viewsContainerData.remove(tag)
+	if gridLayout.created {
 		switch tag {
 		case CellWidth:
 			updateCSSProperty(gridLayout.htmlID(), `grid-template-columns`,
@@ -230,6 +232,7 @@ func (gridLayout *gridLayoutData) remove(tag string) {
 				gridLayout.gridCellSizesCSS(CellHeight, gridLayout.session), gridLayout.session)
 
 		}
+	}
 }
 
 func (gridLayout *gridLayoutData) Set(tag string, value interface{}) bool {
@@ -243,10 +246,15 @@ func (gridLayout *gridLayoutData) set(tag string, value interface{}) bool {
 	}
 
 	if tag == Gap {
-		return gridLayout.set(GridRowGap, value) && gridLayout.set(GridColumnGap, value)
+		if gridLayout.set(GridRowGap, value) && gridLayout.set(GridColumnGap, value) {
+			gridLayout.propertyChangedEvent(Gap)
+			return true
+		}
+		return false
 	}
 
 	if gridLayout.viewsContainerData.set(tag, value) {
+		if gridLayout.created {
 			switch tag {
 			case CellWidth:
 				updateCSSProperty(gridLayout.htmlID(), `grid-template-columns`,
@@ -257,6 +265,7 @@ func (gridLayout *gridLayoutData) set(tag string, value interface{}) bool {
 					gridLayout.gridCellSizesCSS(CellHeight, gridLayout.session), gridLayout.session)
 
 			}
+		}
 		return true
 	}
 

imageView.go

@@ -67,7 +67,7 @@ func (imageView *imageViewData) normalizeTag(tag string) string {
 	case HorizontalAlign:
 		tag = ImageHorizontalAlign
 
-	case altProperty:
+	case altTag:
 		tag = AltText
 	}
 	return tag
@@ -79,6 +79,7 @@ func (imageView *imageViewData) Remove(tag string) {
 
 func (imageView *imageViewData) remove(tag string) {
 	imageView.viewData.remove(tag)
+	if imageView.created {
 		switch tag {
 		case Source:
 			updateProperty(imageView.htmlID(), "src", "", imageView.session)
@@ -90,6 +91,7 @@ func (imageView *imageViewData) remove(tag string) {
 		case ImageVerticalAlign, ImageHorizontalAlign:
 			updateCSSStyle(imageView.htmlID(), imageView.session)
 		}
+	}
 }
 
 func (imageView *imageViewData) Set(tag string, value interface{}) bool {
@@ -106,30 +108,38 @@ func (imageView *imageViewData) set(tag string, value interface{}) bool {
 	case Source:
 		if text, ok := value.(string); ok {
 			imageView.properties[Source] = text
+			if imageView.created {
 				updateProperty(imageView.htmlID(), "src", text, imageView.session)
 				if srcset := imageView.srcSet(text); srcset != "" {
 					updateProperty(imageView.htmlID(), "srcset", srcset, imageView.session)
 				} else {
 					removeProperty(imageView.htmlID(), "srcset", imageView.session)
 				}
+			}
+			imageView.propertyChangedEvent(Source)
 			return true
 		}
-		notCompatibleType(tag, value)
+		notCompatibleType(Source, value)
 
 	case AltText:
 		if text, ok := value.(string); ok {
 			imageView.properties[AltText] = text
+			if imageView.created {
 				updateInnerHTML(imageView.htmlID(), imageView.session)
+			}
+			imageView.propertyChangedEvent(Source)
 			return true
 		}
 		notCompatibleType(tag, value)
 
 	default:
 		if imageView.viewData.set(tag, value) {
+			if imageView.created {
 				switch tag {
 				case ImageVerticalAlign, ImageHorizontalAlign:
 					updateCSSStyle(imageView.htmlID(), imageView.session)
 				}
+			}
 			return true
 		}
 	}

listAdapter.go

@@ -77,7 +77,7 @@ func (adapter *viewListAdapter) ListItem(index int, session Session) View {
 
 func (adapter *viewListAdapter) IsListItemEnabled(index int) bool {
 	if index >= 0 && index < len(adapter.items) {
-		return !IsDisabled(adapter.items[index])
+		return !IsDisabled(adapter.items[index], "")
 	}
 	return true
 }

listLayout.go

@@ -55,10 +55,12 @@ func (listLayout *listLayoutData) Remove(tag string) {
 
 func (listLayout *listLayoutData) remove(tag string) {
 	listLayout.viewsContainerData.remove(tag)
+	if listLayout.created {
 		switch tag {
 		case Orientation, Wrap, HorizontalAlign, VerticalAlign:
 			updateCSSStyle(listLayout.htmlID(), listLayout.session)
 		}
+	}
 }
 
 func (listLayout *listLayoutData) Set(tag string, value interface{}) bool {
@@ -72,10 +74,12 @@ func (listLayout *listLayoutData) set(tag string, value interface{}) bool {
 	}
 
 	if listLayout.viewsContainerData.set(tag, value) {
+		if listLayout.created {
 			switch tag {
 			case Orientation, Wrap, HorizontalAlign, VerticalAlign:
 				updateCSSStyle(listLayout.htmlID(), listLayout.session)
 			}
+		}
 		return true
 	}
 	return false

listView.go

@@ -114,46 +114,71 @@ func (listView *listViewData) Remove(tag string) {
 func (listView *listViewData) remove(tag string) {
 	switch tag {
 	case Checked:
+		if len(listView.checkedItem) > 0 {
 			listView.checkedItem = []int{}
+			if listView.created {
 				updateInnerHTML(listView.htmlID(), listView.session)
+			}
+			listView.propertyChangedEvent(tag)
+		}
 
 	case Items:
+		if listView.adapter != nil {
 			listView.adapter = nil
+			if listView.created {
 				updateInnerHTML(listView.htmlID(), listView.session)
+			}
+			listView.propertyChangedEvent(tag)
+		}
 
 	case Orientation, Wrap:
+		if _, ok := listView.properties[tag]; ok {
 			delete(listView.properties, tag)
+			if listView.created {
 				updateCSSStyle(listView.htmlID(), listView.session)
+			}
+			listView.propertyChangedEvent(tag)
+		}
 
 	case Current:
 		current := GetListViewCurrent(listView, "")
 		delete(listView.properties, tag)
+		if listView.created {
 			updateInnerHTML(listView.htmlID(), listView.session)
+		}
 		if current != -1 {
 			for _, listener := range listView.selectedListeners {
 				listener(listView, -1)
 			}
+			listView.propertyChangedEvent(tag)
 		}
 
 	case ItemWidth, ItemHeight, ItemHorizontalAlign, ItemVerticalAlign, ItemCheckbox,
 		CheckboxHorizontalAlign, CheckboxVerticalAlign, ListItemStyle, CurrentStyle, CurrentInactiveStyle:
-
+		if _, ok := listView.properties[tag]; ok {
 			delete(listView.properties, tag)
+			if listView.created {
 				updateInnerHTML(listView.htmlID(), listView.session)
+			}
+			listView.propertyChangedEvent(tag)
+		}
 
 	case ListItemClickedEvent:
 		if len(listView.clickedListeners) > 0 {
 			listView.clickedListeners = []func(ListView, int){}
+			listView.propertyChangedEvent(tag)
 		}
 
 	case ListItemSelectedEvent:
 		if len(listView.selectedListeners) > 0 {
 			listView.selectedListeners = []func(ListView, int){}
+			listView.propertyChangedEvent(tag)
 		}
 
 	case ListItemCheckedEvent:
 		if len(listView.checkedListeners) > 0 {
 			listView.checkedListeners = []func(ListView, []int){}
+			listView.propertyChangedEvent(tag)
 		}
 
 	default:
@@ -171,10 +196,7 @@ func (listView *listViewData) set(tag string, value interface{}) bool {
 		return true
 	}
 
-	result := false
-
 	switch tag {
-
 	case ListItemClickedEvent:
 		listeners := listView.valueToItemListeners(value)
 		if listeners == nil {
@@ -182,6 +204,7 @@ func (listView *listViewData) set(tag string, value interface{}) bool {
 			return false
 		}
 		listView.clickedListeners = listeners
+		listView.propertyChangedEvent(tag)
 		return true
 
 	case ListItemSelectedEvent:
@@ -191,44 +214,56 @@ func (listView *listViewData) set(tag string, value interface{}) bool {
 			return false
 		}
 		listView.selectedListeners = listeners
+		listView.propertyChangedEvent(tag)
 		return true
 
 	case ListItemCheckedEvent:
-		return listView.setItemCheckedEvent(value)
+		if !listView.setItemCheckedEvent(value) {
+			return false
+		}
+		listView.propertyChangedEvent(tag)
+		return true
 
 	case Checked:
-		return listView.setChecked(value)
+		if !listView.setChecked(value) {
+			return false
+		}
 
 	case Items:
-		result = listView.setItems(value)
+		if !listView.setItems(value) {
+			return false
+		}
 
 	case Current:
 		oldCurrent := GetListViewCurrent(listView, "")
-		if listView.setIntProperty(Current, value) {
+		if !listView.setIntProperty(Current, value) {
+			return false
+		}
 		current := GetListViewCurrent(listView, "")
-			if oldCurrent != current {
+		if oldCurrent == current {
-				updateInnerHTML(listView.htmlID(), listView.session)
-				for _, listener := range listView.selectedListeners {
-					listener(listView, current)
-				}
-			}
 			return true
 		}
 
-	case Orientation, Wrap, VerticalAlign, HorizontalAlign, Style, StyleDisabled:
+		for _, listener := range listView.selectedListeners {
-		result = listView.viewData.set(tag, value)
+			listener(listView, current)
+		}
 
-	case ItemWidth, ItemHeight:
+	case Orientation, Wrap, VerticalAlign, HorizontalAlign, Style, StyleDisabled, ItemWidth, ItemHeight:
-		result = listView.setSizeProperty(tag, value)
+		result := listView.viewData.set(tag, value)
+		if result && listView.created {
+			updateInnerHTML(listView.htmlID(), listView.session)
+		}
+		return result
 
 	case ItemHorizontalAlign, ItemVerticalAlign, ItemCheckbox, CheckboxHorizontalAlign, CheckboxVerticalAlign:
-		result = listView.setEnumProperty(tag, value, enumProperties[tag].values)
+		if !listView.setEnumProperty(tag, value, enumProperties[tag].values) {
+			return false
+		}
 
 	case ListItemStyle, CurrentStyle, CurrentInactiveStyle:
 		switch value := value.(type) {
 		case string:
 			listView.properties[tag] = value
-			result = true
 
 		default:
 			notCompatibleType(tag, value)
@@ -239,11 +274,11 @@ func (listView *listViewData) set(tag string, value interface{}) bool {
 		return listView.viewData.set(tag, value)
 	}
 
-	if result {
+	if listView.created {
 		updateInnerHTML(listView.htmlID(), listView.session)
 	}
-
+	listView.propertyChangedEvent(tag)
-	return result
+	return true
 }
 
 func (listView *listViewData) setItemCheckedEvent(value interface{}) bool {
@@ -1054,14 +1089,18 @@ func (listView *listViewData) handleCommand(self View, command string, data Data
 				for _, listener := range listView.selectedListeners {
 					listener(listView, number)
 				}
+				listView.propertyChangedEvent(Current)
 			}
 		}
 
 	case "itemUnselected":
+		if _, ok := listView.properties[Current]; ok {
 			delete(listView.properties, Current)
 			for _, listener := range listView.selectedListeners {
 				listener(listView, -1)
 			}
+			listView.propertyChangedEvent(Current)
+		}
 
 	case "itemClick":
 		listView.onItemClick()
@@ -1075,7 +1114,7 @@ func (listView *listViewData) handleCommand(self View, command string, data Data
 
 func (listView *listViewData) onItemClick() {
 	current := GetListViewCurrent(listView, "")
-	if current >= 0 && !IsDisabled(listView) {
+	if current >= 0 && !IsDisabled(listView, "") {
 		checkbox := GetListViewCheckbox(listView, "")
 	m:
 		switch checkbox {
@@ -1115,6 +1154,7 @@ func (listView *listViewData) onItemClick() {
 			for _, listener := range listView.checkedListeners {
 				listener(listView, listView.checkedItem)
 			}
+			listView.propertyChangedEvent(Checked)
 		}
 		for _, listener := range listView.clickedListeners {
 			listener(listView, current)

mediaPlayer.go

@@ -173,20 +173,8 @@ func (player *mediaPlayerData) Remove(tag string) {
 }
 
 func (player *mediaPlayerData) remove(tag string) {
-	switch tag {
-
-	case Controls, Loop, Muted, Preload, AbortEvent, LoadStartEvent, PlayerErrorEvent,
-		CanPlayEvent, CanPlayThroughEvent, CompleteEvent, DurationChangedEvent,
-		EmptiedEvent, EndedEvent, LoadedDataEvent, LoadedMetadataEvent, PauseEvent, PlayEvent,
-		PlayingEvent, RateChangedEvent, SeekedEvent, SeekingEvent, StalledEvent, SuspendEvent,
-		ProgressEvent, TimeUpdateEvent, VolumeChangedEvent, WaitingEvent:
-
 	player.viewData.remove(tag)
 	player.propertyChanged(tag)
-
-	default:
-		player.viewData.remove(tag)
-	}
 }
 
 func (player *mediaPlayerData) Set(tag string, value interface{}) bool {
@@ -216,6 +204,7 @@ func (player *mediaPlayerData) set(tag string, value interface{}) bool {
 				player.properties[tag] = listeners
 			}
 			player.propertyChanged(tag)
+			player.propertyChangedEvent(tag)
 			return true
 		}
 		notCompatibleType(tag, value)
@@ -228,6 +217,7 @@ func (player *mediaPlayerData) set(tag string, value interface{}) bool {
 				player.properties[tag] = listeners
 			}
 			player.propertyChanged(tag)
+			player.propertyChangedEvent(tag)
 			return true
 		}
 		notCompatibleType(tag, value)
@@ -240,6 +230,7 @@ func (player *mediaPlayerData) set(tag string, value interface{}) bool {
 				player.properties[tag] = listeners
 			}
 			player.propertyChanged(tag)
+			player.propertyChangedEvent(tag)
 			return true
 		}
 		notCompatibleType(tag, value)
@@ -247,14 +238,14 @@ func (player *mediaPlayerData) set(tag string, value interface{}) bool {
 	case Source:
 		if player.setSource(value) {
 			player.propertyChanged(tag)
+			player.propertyChangedEvent(tag)
 			return true
 		}
 
 	default:
-		if player.viewData.set(tag, value) {
+		return player.viewData.set(tag, value)
-			return true
-		}
 	}
+
 	return false
 }
 
@@ -657,6 +648,7 @@ func playerEvents() []struct{ tag, cssTag string } {
 }
 
 func (player *mediaPlayerData) propertyChanged(tag string) {
+	if player.created {
 		switch tag {
 		case Controls, Loop:
 			value, _ := boolProperty(player, tag, player.Session())
@@ -737,9 +729,7 @@ func (player *mediaPlayerData) propertyChanged(tag string) {
 
 		case Source:
 			updateInnerHTML(player.htmlID(), player.Session())
-
+		}
-	default:
-		player.viewData.propertyChanged(tag)
 	}
 }
 

numberPicker.go

@@ -69,6 +69,7 @@ func (picker *numberPickerData) remove(tag string) {
 	case NumberChangedEvent:
 		if len(picker.numberChangedListeners) > 0 {
 			picker.numberChangedListeners = []func(NumberPicker, float64){}
+			picker.propertyChangedEvent(tag)
 		}
 
 	default:
@@ -135,18 +136,21 @@ func (picker *numberPickerData) set(tag string, value interface{}) bool {
 			}
 			picker.numberChangedListeners = listeners
 		}
+		picker.propertyChangedEvent(tag)
 		return true
 
 	case NumberPickerValue:
 		oldValue := GetNumberPickerValue(picker, "")
 		min, max := GetNumberPickerMinMax(picker, "")
 		if picker.setFloatProperty(NumberPickerValue, value, min, max) {
-			newValue := GetNumberPickerValue(picker, "")
+			if newValue := GetNumberPickerValue(picker, ""); oldValue != newValue {
-			if oldValue != newValue {
+				if picker.created {
 					picker.session.runScript(fmt.Sprintf(`setInputValue('%s', '%f')`, picker.htmlID(), newValue))
+				}
 				for _, listener := range picker.numberChangedListeners {
 					listener(picker, newValue)
 				}
+				picker.propertyChangedEvent(tag)
 			}
 			return true
 		}
@@ -161,6 +165,7 @@ func (picker *numberPickerData) set(tag string, value interface{}) bool {
 }
 
 func (picker *numberPickerData) propertyChanged(tag string) {
+	if picker.created {
 		switch tag {
 		case NumberPickerType:
 			if GetNumberPickerType(picker, "") == NumberSlider {
@@ -191,6 +196,7 @@ func (picker *numberPickerData) propertyChanged(tag string) {
 				listener(picker, value)
 			}
 		}
+	}
 }
 
 func (picker *numberPickerData) Get(tag string) interface{} {
@@ -246,7 +252,7 @@ func (picker *numberPickerData) htmlProperties(self View, buffer *strings.Builde
 }
 
 func (picker *numberPickerData) htmlDisabledProperties(self View, buffer *strings.Builder) {
-	if IsDisabled(self) {
+	if IsDisabled(self, "") {
 		buffer.WriteString(` disabled`)
 	}
 	picker.viewData.htmlDisabledProperties(self, buffer)

progressBar.go

@@ -58,6 +58,7 @@ func (progress *progressBarData) remove(tag string) {
 }
 
 func (progress *progressBarData) propertyChanged(tag string) {
+	if progress.created {
 		switch tag {
 		case ProgressBarMax:
 			updateProperty(progress.htmlID(), Max, strconv.FormatFloat(GetProgressBarMax(progress, ""), 'f', -1, 32), progress.session)
@@ -65,6 +66,7 @@ func (progress *progressBarData) propertyChanged(tag string) {
 		case ProgressBarValue:
 			updateProperty(progress.htmlID(), Value, strconv.FormatFloat(GetProgressBarValue(progress, ""), 'f', -1, 32), progress.session)
 		}
+	}
 }
 
 func (progress *progressBarData) Set(tag string, value interface{}) bool {

propertyNames.go

@@ -368,7 +368,7 @@ const (
 	CenterY = "center-y"
 	// AltText is the constant for the "alt-text" property tag.
 	AltText = "alt-text"
-	altProperty = "alt"
+	altTag  = "alt"
 	// AvoidBreak is the constant for the "avoid-break" property tag.
 	// The "avoid-break" bool property sets how region breaks should behave inside a generated box.
 	// If the property value is "true" then fvoids any break from being inserted within the principal box.

propertySet.go

@@ -65,6 +65,7 @@ var intProperties = []string{
 	FootHeight,
 	RowSpan,
 	ColumnSpan,
+	ColumnCount,
 }
 
 var floatProperties = map[string]struct{ min, max float64 }{

resizable.go

@@ -75,22 +75,29 @@ func (resizable *resizableData) remove(tag string) {
 		oldSide := resizable.getSide()
 		delete(resizable.properties, Side)
 		if oldSide != resizable.getSide() {
+			if resizable.created {
 				updateInnerHTML(resizable.htmlID(), resizable.Session())
 				resizable.updateResizeBorderWidth()
 			}
+			resizable.propertyChangedEvent(tag)
+		}
 
 	case ResizeBorderWidth:
 		w := resizable.resizeBorderWidth()
 		delete(resizable.properties, ResizeBorderWidth)
 		if !w.Equal(resizable.resizeBorderWidth()) {
 			resizable.updateResizeBorderWidth()
+			resizable.propertyChangedEvent(tag)
 		}
 
 	case Content:
 		if len(resizable.content) > 0 {
 			resizable.content = []View{}
+			if resizable.created {
 				updateInnerHTML(resizable.htmlID(), resizable.Session())
 			}
+			resizable.propertyChangedEvent(tag)
+		}
 
 	default:
 		resizable.viewData.remove(tag)
@@ -110,20 +117,25 @@ func (resizable *resizableData) set(tag string, value interface{}) bool {
 	switch tag {
 	case Side:
 		oldSide := resizable.getSide()
-		ok := resizable.setSide(value)
+		if !resizable.setSide(value) {
-		if ok && oldSide != resizable.getSide() {
+			notCompatibleType(tag, value)
+			return false
+		}
+		if oldSide != resizable.getSide() {
+			if resizable.created {
 				updateInnerHTML(resizable.htmlID(), resizable.Session())
 				resizable.updateResizeBorderWidth()
-		} else {
-			notCompatibleType(tag, value)
 			}
-		return ok
+			resizable.propertyChangedEvent(tag)
+		}
+		return true
 
 	case ResizeBorderWidth:
 		w := resizable.resizeBorderWidth()
 		ok := resizable.setSizeProperty(tag, value)
 		if ok && !w.Equal(resizable.resizeBorderWidth()) {
 			resizable.updateResizeBorderWidth()
+			resizable.propertyChangedEvent(tag)
 		}
 		return ok
 
@@ -139,18 +151,25 @@ func (resizable *resizableData) set(tag string, value interface{}) bool {
 		case DataObject:
 			if view := CreateViewFromObject(resizable.Session(), value); view != nil {
 				newContent = view
-			}
+			} else {
+				return false
+			}
+
+		default:
+			notCompatibleType(tag, value)
+			return false
 		}
 
-		if newContent != nil {
 		if len(resizable.content) == 0 {
 			resizable.content = []View{newContent}
 		} else {
 			resizable.content[0] = newContent
 		}
+		if resizable.created {
 			updateInnerHTML(resizable.htmlID(), resizable.Session())
-			return true
 		}
+		resizable.propertyChangedEvent(tag)
+		return true
 
 	case CellWidth, CellHeight, GridRowGap, GridColumnGap, CellVerticalAlign, CellHorizontalAlign:
 		ErrorLogF(`Not supported "%s" property`, tag)
@@ -306,12 +325,14 @@ func (resizable *resizableData) resizeBorderWidth() SizeUnit {
 }
 
 func (resizable *resizableData) updateResizeBorderWidth() {
+	if resizable.created {
 		htmlID := resizable.htmlID()
 		session := resizable.Session()
 		column, row := resizable.cellSizeCSS()
 
 		updateCSSProperty(htmlID, "grid-template-columns", column, session)
 		updateCSSProperty(htmlID, "grid-template-rows", row, session)
+	}
 }
 
 func (resizable *resizableData) cellSizeCSS() (string, string) {

stackLayout.go

@@ -6,6 +6,8 @@ import (
 	"strings"
 )
 
+// TODO PeekChangedEvent
+
 const (
 	// DefaultAnimation - default animation of StackLayout push
 	DefaultAnimation = 0
@@ -93,23 +95,33 @@ func (layout *stackLayoutData) popFinished(view View, tag string) {
 }
 
 func (layout *stackLayoutData) Set(tag string, value interface{}) bool {
-	if strings.ToLower(tag) == TransitionEndEvent {
+	return layout.set(strings.ToLower(tag), value)
+}
+
+func (layout *stackLayoutData) set(tag string, value interface{}) bool {
+	if tag == TransitionEndEvent {
 		listeners, ok := valueToAnimationListeners(value)
 		if ok {
 			listeners = append(listeners, layout.pushFinished)
 			listeners = append(listeners, layout.popFinished)
 			layout.properties[TransitionEndEvent] = listeners
+			layout.propertyChangedEvent(TransitionEndEvent)
 		}
 		return ok
 	}
-	return layout.viewsContainerData.Set(tag, value)
+	return layout.viewsContainerData.set(tag, value)
 }
 
 func (layout *stackLayoutData) Remove(tag string) {
-	if strings.ToLower(tag) == TransitionEndEvent {
+	layout.remove(strings.ToLower(tag))
+}
+
+func (layout *stackLayoutData) remove(tag string) {
+	if tag == TransitionEndEvent {
 		layout.properties[TransitionEndEvent] = []func(View, string){layout.pushFinished, layout.popFinished}
+		layout.propertyChangedEvent(TransitionEndEvent)
 	} else {
-		layout.viewsContainerData.Remove(tag)
+		layout.viewsContainerData.remove(tag)
 	}
 }
 
@@ -238,6 +250,7 @@ func (layout *stackLayoutData) Push(view View, animation int, onPushFinished fun
 
 	layout.views = append(layout.views, view)
 	view.setParentID(htmlID)
+	layout.propertyChangedEvent(Content)
 }
 
 func (layout *stackLayoutData) Pop(animation int, onPopFinished func(View)) bool {
@@ -286,6 +299,7 @@ func (layout *stackLayoutData) Pop(animation int, onPopFinished func(View)) bool
 	}
 
 	updateCSSProperty(htmlID+"pop", "transform", value, layout.session)
+	layout.propertyChangedEvent(Content)
 	return true
 }
 

tableView.go

@@ -168,35 +168,51 @@ func (table *tableViewData) Init(session Session) {
 	table.tag = "TableView"
 }
 
+func (table *tableViewData) normalizeTag(tag string) string {
+	switch tag = strings.ToLower(tag); tag {
+	case "top-cell-padding":
+		tag = CellPaddingTop
+
+	case "right-cell-padding":
+		tag = CellPaddingRight
+
+	case "bottom-cell-padding":
+		tag = CellPaddingBottom
+
+	case "left-cell-padding":
+		tag = CellPaddingLeft
+	}
+	return tag
+}
+
 func (table *tableViewData) Get(tag string) interface{} {
-	return table.get(strings.ToLower(tag))
+	return table.get(table.normalizeTag(tag))
 }
 
 func (table *tableViewData) Remove(tag string) {
-	table.remove(strings.ToLower(tag))
+	table.remove(table.normalizeTag(tag))
 }
 
 func (table *tableViewData) remove(tag string) {
 	switch tag {
-
+	case CellPaddingTop, CellPaddingRight, CellPaddingBottom, CellPaddingLeft:
-	case CellPaddingTop, CellPaddingRight, CellPaddingBottom, CellPaddingLeft,
-		"top-cell-padding", "right-cell-padding", "bottom-cell-padding", "left-cell-padding":
 		table.removeBoundsSide(CellPadding, tag)
+		table.propertyChanged(tag)
 
 	case Gap, CellBorder, CellPadding, RowStyle, ColumnStyle, CellStyle,
 		HeadHeight, HeadStyle, FootHeight, FootStyle:
+		if _, ok := table.properties[tag]; ok {
 			delete(table.properties, tag)
+			table.propertyChanged(tag)
+		}
 
 	default:
 		table.viewData.remove(tag)
-		return
 	}
-
-	table.propertyChanged(tag)
 }
 
 func (table *tableViewData) Set(tag string, value interface{}) bool {
-	return table.set(strings.ToLower(tag), value)
+	return table.set(table.normalizeTag(tag), value)
 }
 
 func (table *tableViewData) set(tag string, value interface{}) bool {
@@ -307,8 +323,7 @@ func (table *tableViewData) set(tag string, value interface{}) bool {
 			return false
 		}
 
-	case CellPaddingTop, CellPaddingRight, CellPaddingBottom, CellPaddingLeft,
+	case CellPaddingTop, CellPaddingRight, CellPaddingBottom, CellPaddingLeft:
-		"top-cell-padding", "right-cell-padding", "bottom-cell-padding", "left-cell-padding":
 		if !table.setBoundsSide(CellPadding, tag, value) {
 			return false
 		}
@@ -336,11 +351,11 @@ func (table *tableViewData) set(tag string, value interface{}) bool {
 }
 
 func (table *tableViewData) propertyChanged(tag string) {
+	if table.created {
 		switch tag {
 		case Content, RowStyle, ColumnStyle, CellStyle, CellPadding, CellBorder,
 			HeadHeight, HeadStyle, FootHeight, FootStyle,
-		CellPaddingTop, CellPaddingRight, CellPaddingBottom, CellPaddingLeft,
+			CellPaddingTop, CellPaddingRight, CellPaddingBottom, CellPaddingLeft:
-		"top-cell-padding", "right-cell-padding", "bottom-cell-padding", "left-cell-padding":
 			table.ReloadTableData()
 
 		case Gap:
@@ -354,8 +369,9 @@ func (table *tableViewData) propertyChanged(tag string) {
 				updateCSSProperty(htmlID, "border-spacing", gap.cssString("0"), session)
 				updateCSSProperty(htmlID, "border-collapse", "separate", session)
 			}
-
 		}
+	}
+	table.propertyChangedEvent(tag)
 }
 
 func (table *tableViewData) htmlTag() string {

tabsLayout.go

@@ -123,15 +123,26 @@ func (tabsLayout *tabsLayoutData) Remove(tag string) {
 func (tabsLayout *tabsLayoutData) remove(tag string) {
 	switch tag {
 	case CurrentTabChangedEvent:
+		if len(tabsLayout.tabListener) > 0 {
 			tabsLayout.tabListener = []func(TabsLayout, int, int){}
+			tabsLayout.propertyChangedEvent(tag)
+		}
+		return
 
 	case TabCloseEvent:
+		if len(tabsLayout.tabCloseListener) > 0 {
 			tabsLayout.tabCloseListener = []func(TabsLayout, int){}
+			tabsLayout.propertyChangedEvent(tag)
+		}
+		return
 
 	case Current:
 		oldCurrent := tabsLayout.currentItem()
 		delete(tabsLayout.properties, Current)
-		if !tabsLayout.session.ignoreViewUpdates() && oldCurrent != 0 {
+		if oldCurrent == 0 {
+			return
+		}
+		if tabsLayout.created {
 			tabsLayout.session.runScript(fmt.Sprintf("activateTab(%v, %d);", tabsLayout.htmlID(), 0))
 			for _, listener := range tabsLayout.tabListener {
 				listener(tabsLayout, 0, oldCurrent)
@@ -140,7 +151,7 @@ func (tabsLayout *tabsLayoutData) remove(tag string) {
 
 	case Tabs:
 		delete(tabsLayout.properties, Tabs)
-		if !tabsLayout.session.ignoreViewUpdates() {
+		if tabsLayout.created {
 			htmlID := tabsLayout.htmlID()
 			updateProperty(htmlID, inactiveTabStyle, tabsLayout.inactiveTabStyle(), tabsLayout.session)
 			updateProperty(htmlID, activeTabStyle, tabsLayout.activeTabStyle(), tabsLayout.session)
@@ -150,7 +161,7 @@ func (tabsLayout *tabsLayoutData) remove(tag string) {
 
 	case TabStyle, CurrentTabStyle:
 		delete(tabsLayout.properties, tag)
-		if !tabsLayout.session.ignoreViewUpdates() {
+		if tabsLayout.created {
 			htmlID := tabsLayout.htmlID()
 			updateProperty(htmlID, inactiveTabStyle, tabsLayout.inactiveTabStyle(), tabsLayout.session)
 			updateProperty(htmlID, activeTabStyle, tabsLayout.activeTabStyle(), tabsLayout.session)
@@ -159,13 +170,16 @@ func (tabsLayout *tabsLayoutData) remove(tag string) {
 
 	case TabCloseButton:
 		delete(tabsLayout.properties, tag)
-		if !tabsLayout.session.ignoreViewUpdates() {
+		if tabsLayout.created {
 			updateInnerHTML(tabsLayout.htmlID(), tabsLayout.session)
 		}
 
 	default:
 		tabsLayout.viewsContainerData.remove(tag)
+		return
 	}
+
+	tabsLayout.propertyChangedEvent(tag)
 }
 
 func (tabsLayout *tabsLayoutData) Set(tag string, value interface{}) bool {
@@ -201,21 +215,22 @@ func (tabsLayout *tabsLayoutData) set(tag string, value interface{}) bool {
 			return false
 		}
 
-		if !tabsLayout.session.ignoreViewUpdates() {
 		current := tabsLayout.currentItem()
-			if oldCurrent != current {
+		if oldCurrent == current {
+			return true
+		}
+		if tabsLayout.created {
 			tabsLayout.session.runScript(fmt.Sprintf("activateTab(%v, %d);", tabsLayout.htmlID(), current))
 			for _, listener := range tabsLayout.tabListener {
 				listener(tabsLayout, current, oldCurrent)
 			}
 		}
-		}
 
 	case Tabs:
 		if !tabsLayout.setEnumProperty(Tabs, value, enumProperties[Tabs].values) {
 			return false
 		}
-		if !tabsLayout.session.ignoreViewUpdates() {
+		if tabsLayout.created {
 			htmlID := tabsLayout.htmlID()
 			updateProperty(htmlID, inactiveTabStyle, tabsLayout.inactiveTabStyle(), tabsLayout.session)
 			updateProperty(htmlID, activeTabStyle, tabsLayout.activeTabStyle(), tabsLayout.session)
@@ -235,7 +250,7 @@ func (tabsLayout *tabsLayoutData) set(tag string, value interface{}) bool {
 			return false
 		}
 
-		if !tabsLayout.session.ignoreViewUpdates() {
+		if tabsLayout.created {
 			htmlID := tabsLayout.htmlID()
 			updateProperty(htmlID, inactiveTabStyle, tabsLayout.inactiveTabStyle(), tabsLayout.session)
 			updateProperty(htmlID, activeTabStyle, tabsLayout.activeTabStyle(), tabsLayout.session)
@@ -246,7 +261,7 @@ func (tabsLayout *tabsLayoutData) set(tag string, value interface{}) bool {
 		if !tabsLayout.setBoolProperty(tag, value) {
 			return false
 		}
-		if !tabsLayout.session.ignoreViewUpdates() {
+		if tabsLayout.created {
 			updateInnerHTML(tabsLayout.htmlID(), tabsLayout.session)
 		}
 
@@ -254,6 +269,7 @@ func (tabsLayout *tabsLayoutData) set(tag string, value interface{}) bool {
 		return tabsLayout.viewsContainerData.set(tag, value)
 	}
 
+	tabsLayout.propertyChangedEvent(tag)
 	return true
 }
 
@@ -905,6 +921,7 @@ func (tabsLayout *tabsLayoutData) handleCommand(self View, command string, data
 					for _, listener := range tabsLayout.tabListener {
 						listener(tabsLayout, number, current)
 					}
+					tabsLayout.propertyChangedEvent(Current)
 				}
 			}
 		}

textView.go

@@ -43,6 +43,7 @@ func (textView *textViewData) Remove(tag string) {
 
 func (textView *textViewData) remove(tag string) {
 	textView.viewData.remove(tag)
+	if textView.created {
 		switch tag {
 		case Text:
 			updateInnerHTML(textView.htmlID(), textView.session)
@@ -50,6 +51,7 @@ func (textView *textViewData) remove(tag string) {
 		case TextOverflow:
 			textView.textOverflowUpdated()
 		}
+	}
 }
 
 func (textView *textViewData) Set(tag string, value interface{}) bool {
@@ -90,16 +92,24 @@ func (textView *textViewData) set(tag string, value interface{}) bool {
 				return false
 			}
 		}
+		if textView.created {
 			updateInnerHTML(textView.htmlID(), textView.session)
-		return true
+		}
 
 	case TextOverflow:
-		if textView.viewData.set(tag, value) {
+		if !textView.viewData.set(tag, value) {
+			return false
+		}
+		if textView.created {
 			textView.textOverflowUpdated()
 		}
+
+	default:
+		return textView.viewData.set(tag, value)
 	}
 
-	return textView.viewData.set(tag, value)
+	textView.propertyChangedEvent(tag)
+	return true
 }
 
 func (textView *textViewData) textOverflowUpdated() {

timePicker.go

@@ -63,28 +63,47 @@ func (picker *timePickerData) remove(tag string) {
 	case TimeChangedEvent:
 		if len(picker.timeChangedListeners) > 0 {
 			picker.timeChangedListeners = []func(TimePicker, time.Time){}
+			picker.propertyChangedEvent(tag)
 		}
+		return
 
 	case TimePickerMin:
 		delete(picker.properties, TimePickerMin)
+		if picker.created {
 			removeProperty(picker.htmlID(), Min, picker.session)
+		}
 
 	case TimePickerMax:
 		delete(picker.properties, TimePickerMax)
+		if picker.created {
 			removeProperty(picker.htmlID(), Max, picker.session)
+		}
 
 	case TimePickerStep:
 		delete(picker.properties, TimePickerMax)
+		if picker.created {
 			removeProperty(picker.htmlID(), Step, picker.session)
+		}
 
 	case TimePickerValue:
+		if _, ok := picker.properties[TimePickerValue]; ok {
 			delete(picker.properties, TimePickerValue)
-		updateProperty(picker.htmlID(), Value, time.Now().Format(timeFormat), picker.session)
+			time := GetTimePickerValue(picker, "")
+			if picker.created {
+				picker.session.runScript(fmt.Sprintf(`setInputValue('%s', '%s')`, picker.htmlID(), time.Format(timeFormat)))
+			}
+			for _, listener := range picker.timeChangedListeners {
+				listener(picker, time)
+			}
+		} else {
+			return
+		}
 
 	default:
 		picker.viewData.remove(tag)
-		picker.propertyChanged(tag)
+		return
 	}
+	picker.propertyChangedEvent(tag)
 }
 
 func (picker *timePickerData) Set(tag string, value interface{}) bool {
@@ -121,8 +140,11 @@ func (picker *timePickerData) set(tag string, value interface{}) bool {
 		old, oldOK := getTimeProperty(picker, TimePickerMin, Min)
 		if time, ok := setTimeValue(TimePickerMin); ok {
 			if !oldOK || time != old {
+				if picker.created {
 					updateProperty(picker.htmlID(), Min, time.Format(timeFormat), picker.session)
 				}
+				picker.propertyChangedEvent(tag)
+			}
 			return true
 		}
 
@@ -130,33 +152,41 @@ func (picker *timePickerData) set(tag string, value interface{}) bool {
 		old, oldOK := getTimeProperty(picker, TimePickerMax, Max)
 		if time, ok := setTimeValue(TimePickerMax); ok {
 			if !oldOK || time != old {
+				if picker.created {
 					updateProperty(picker.htmlID(), Max, time.Format(timeFormat), picker.session)
 				}
+				picker.propertyChangedEvent(tag)
+			}
 			return true
 		}
 
 	case TimePickerStep:
 		oldStep := GetTimePickerStep(picker, "")
 		if picker.setIntProperty(TimePickerStep, value) {
-			step := GetTimePickerStep(picker, "")
+			if step := GetTimePickerStep(picker, ""); oldStep != step {
-			if oldStep != step {
+				if picker.created {
 					if step > 0 {
 						updateProperty(picker.htmlID(), Step, strconv.Itoa(step), picker.session)
 					} else {
 						removeProperty(picker.htmlID(), Step, picker.session)
 					}
 				}
+				picker.propertyChangedEvent(tag)
+			}
 			return true
 		}
 
 	case TimePickerValue:
 		oldTime := GetTimePickerValue(picker, "")
 		if time, ok := setTimeValue(TimePickerMax); ok {
-			picker.session.runScript(fmt.Sprintf(`setInputValue('%s', '%s')`, picker.htmlID(), time.Format(timeFormat)))
 			if time != oldTime {
+				if picker.created {
+					picker.session.runScript(fmt.Sprintf(`setInputValue('%s', '%s')`, picker.htmlID(), time.Format(timeFormat)))
+				}
 				for _, listener := range picker.timeChangedListeners {
 					listener(picker, time)
 				}
+				picker.propertyChangedEvent(tag)
 			}
 			return true
 		}
@@ -167,8 +197,8 @@ func (picker *timePickerData) set(tag string, value interface{}) bool {
 			picker.timeChangedListeners = []func(TimePicker, time.Time){value}
 
 		case func(time.Time):
-			fn := func(view TimePicker, date time.Time) {
+			fn := func(view TimePicker, time time.Time) {
-				value(date)
+				value(time)
 			}
 			picker.timeChangedListeners = []func(TimePicker, time.Time){fn}
 
@@ -183,8 +213,8 @@ func (picker *timePickerData) set(tag string, value interface{}) bool {
 					return false
 				}
 
-				listeners[i] = func(view TimePicker, date time.Time) {
+				listeners[i] = func(view TimePicker, time time.Time) {
-					val(date)
+					val(time)
 				}
 			}
 			picker.timeChangedListeners = listeners
@@ -202,8 +232,8 @@ func (picker *timePickerData) set(tag string, value interface{}) bool {
 					listeners[i] = val
 
 				case func(time.Time):
-					listeners[i] = func(view TimePicker, date time.Time) {
+					listeners[i] = func(view TimePicker, time time.Time) {
-						val(date)
+						val(time)
 					}
 
 				default:
@@ -213,13 +243,11 @@ func (picker *timePickerData) set(tag string, value interface{}) bool {
 			}
 			picker.timeChangedListeners = listeners
 		}
+		picker.propertyChangedEvent(tag)
 		return true
 
 	default:
-		if picker.viewData.set(tag, value) {
+		return picker.viewData.set(tag, value)
-			picker.propertyChanged(tag)
-			return true
-		}
 	}
 	return false
 }
@@ -273,7 +301,7 @@ func (picker *timePickerData) htmlProperties(self View, buffer *strings.Builder)
 }
 
 func (picker *timePickerData) htmlDisabledProperties(self View, buffer *strings.Builder) {
-	if IsDisabled(self) {
+	if IsDisabled(self, "") {
 		buffer.WriteString(` disabled`)
 	}
 	picker.viewData.htmlDisabledProperties(self, buffer)

view.go

@@ -57,6 +57,8 @@ type View interface {
 	// a description of the error is written to the log
 	SetAnimated(tag string, value interface{}, animation Animation) bool
 
+	SetChangeListener(tag string, listener func(View, string))
+
 	handleCommand(self View, command string, data DataObject) bool
 	//updateEventHandlers()
 	htmlClass(disabled bool) string
@@ -87,6 +89,7 @@ type viewData struct {
 	_htmlID          string
 	parentID         string
 	systemClass      string
+	changeListener   map[string]func(View, string)
 	singleTransition map[string]Animation
 	addCSS           map[string]string
 	frame            Frame
@@ -129,6 +132,7 @@ func (view *viewData) Init(session Session) {
 	view.viewStyle.init()
 	view.tag = "View"
 	view.session = session
+	view.changeListener = map[string]func(View, string){}
 	view.addCSS = map[string]string{}
 	//view.animation = map[string]AnimationEndListener{}
 	view.singleTransition = map[string]Animation{}
@@ -186,7 +190,7 @@ func (view *viewData) remove(tag string) {
 	case Style, StyleDisabled:
 		if _, ok := view.properties[tag]; ok {
 			delete(view.properties, tag)
-			updateProperty(view.htmlID(), "class", view.htmlClass(IsDisabled(view)), view.session)
+			updateProperty(view.htmlID(), "class", view.htmlClass(IsDisabled(view, "")), view.session)
 		}
 
 	case FocusEvent, LostFocusEvent:
@@ -221,8 +225,62 @@ func (view *viewData) remove(tag string) {
 
 	default:
 		view.viewStyle.remove(tag)
-		view.propertyChanged(tag)
+		viewPropertyChanged(view, tag)
 	}
+
+	view.propertyChangedEvent(tag)
+}
+
+func (view *viewData) propertyChangedEvent(tag string) {
+	if listener, ok := view.changeListener[tag]; ok {
+		listener(view, tag)
+	}
+
+	switch tag {
+	case BorderLeft, BorderRight, BorderTop, BorderBottom,
+		BorderStyle, BorderLeftStyle, BorderRightStyle, BorderTopStyle, BorderBottomStyle,
+		BorderColor, BorderLeftColor, BorderRightColor, BorderTopColor, BorderBottomColor,
+		BorderWidth, BorderLeftWidth, BorderRightWidth, BorderTopWidth, BorderBottomWidth:
+		tag = Border
+
+	case CellBorderStyle, CellBorderColor, CellBorderWidth,
+		CellBorderLeft, CellBorderLeftStyle, CellBorderLeftColor, CellBorderLeftWidth,
+		CellBorderRight, CellBorderRightStyle, CellBorderRightColor, CellBorderRightWidth,
+		CellBorderTop, CellBorderTopStyle, CellBorderTopColor, CellBorderTopWidth,
+		CellBorderBottom, CellBorderBottomStyle, CellBorderBottomColor, CellBorderBottomWidth:
+		tag = CellBorder
+
+	case OutlineColor, OutlineStyle, OutlineWidth:
+		tag = Outline
+
+	case RadiusX, RadiusY, RadiusTopLeft, RadiusTopLeftX, RadiusTopLeftY,
+		RadiusTopRight, RadiusTopRightX, RadiusTopRightY,
+		RadiusBottomLeft, RadiusBottomLeftX, RadiusBottomLeftY,
+		RadiusBottomRight, RadiusBottomRightX, RadiusBottomRightY:
+		tag = Radius
+
+	case MarginTop, MarginRight, MarginBottom, MarginLeft,
+		"top-margin", "right-margin", "bottom-margin", "left-margin":
+		tag = Margin
+
+	case PaddingTop, PaddingRight, PaddingBottom, PaddingLeft,
+		"top-padding", "right-padding", "bottom-padding", "left-padding":
+		tag = Padding
+
+	case CellPaddingTop, CellPaddingRight, CellPaddingBottom, CellPaddingLeft:
+		tag = CellPadding
+
+	case ColumnSeparatorStyle, ColumnSeparatorWidth, ColumnSeparatorColor:
+		tag = ColumnSeparator
+
+	default:
+		return
+	}
+
+	if listener, ok := view.changeListener[tag]; ok {
+		listener(view, tag)
+	}
+
 }
 
 func (view *viewData) Set(tag string, value interface{}) bool {
@@ -235,64 +293,71 @@ func (view *viewData) set(tag string, value interface{}) bool {
 		return true
 	}
 
+	result := func(res bool) bool {
+		if res {
+			view.propertyChangedEvent(tag)
+		}
+		return res
+	}
+
 	switch tag {
 	case ID:
-		if text, ok := value.(string); ok {
+		text, ok := value.(string)
-			view.viewID = text
+		if !ok {
-			return true
-		}
 			notCompatibleType(ID, value)
 			return false
+		}
+		view.viewID = text
 
 	case Style, StyleDisabled:
-		if text, ok := value.(string); ok {
+		text, ok := value.(string)
-			view.properties[tag] = text
+		if !ok {
-			//updateInnerHTML(view.parentID, view.session)
-			if view.created {
-				updateProperty(view.htmlID(), "class", view.htmlClass(IsDisabled(view)), view.session)
-			}
-			return true
-		}
 			notCompatibleType(ID, value)
 			return false
+		}
+		view.properties[tag] = text
+		if view.created {
+			updateProperty(view.htmlID(), "class", view.htmlClass(IsDisabled(view, "")), view.session)
+		}
 
 	case FocusEvent, LostFocusEvent:
-		return view.setFocusListener(tag, value)
+		return result(view.setFocusListener(tag, value))
 
 	case KeyDownEvent, KeyUpEvent:
-		return view.setKeyListener(tag, value)
+		return result(view.setKeyListener(tag, value))
 
 	case ClickEvent, DoubleClickEvent, MouseDown, MouseUp, MouseMove, MouseOut, MouseOver, ContextMenuEvent:
-		return view.setMouseListener(tag, value)
+		return result(view.setMouseListener(tag, value))
 
 	case PointerDown, PointerUp, PointerMove, PointerOut, PointerOver, PointerCancel:
-		return view.setPointerListener(tag, value)
+		return result(view.setPointerListener(tag, value))
 
 	case TouchStart, TouchEnd, TouchMove, TouchCancel:
-		return view.setTouchListener(tag, value)
+		return result(view.setTouchListener(tag, value))
 
 	case TransitionRunEvent, TransitionStartEvent, TransitionEndEvent, TransitionCancelEvent:
-		return view.setTransitionListener(tag, value)
+		return result(view.setTransitionListener(tag, value))
 
 	case AnimationStartEvent, AnimationEndEvent, AnimationIterationEvent, AnimationCancelEvent:
-		return view.setAnimationListener(tag, value)
+		return result(view.setAnimationListener(tag, value))
 
 	case ResizeEvent, ScrollEvent:
-		return view.setFrameListener(tag, value)
+		return result(view.setFrameListener(tag, value))
-	}
-
-	if view.viewStyle.set(tag, value) {
-		if view.created {
-			view.propertyChanged(tag)
-		}
-		return true
-	}
 
+	default:
+		if !view.viewStyle.set(tag, value) {
 			return false
+		}
+		if view.created {
+			viewPropertyChanged(view, tag)
+		}
+	}
+
+	view.propertyChangedEvent(tag)
+	return true
 }
 
-func (view *viewData) propertyChanged(tag string) {
+func viewPropertyChanged(view *viewData, tag string) {
-
 	if view.updateTransformProperty(tag) {
 		return
 	}
@@ -446,7 +511,7 @@ func (view *viewData) propertyChanged(tag string) {
 	case Strikethrough, Overline, Underline:
 		updateCSSProperty(htmlID, "text-decoration", view.cssTextDecoration(session), session)
 		for _, tag2 := range []string{TextLineColor, TextLineStyle, TextLineThickness} {
-			view.propertyChanged(tag2)
+			viewPropertyChanged(view, tag2)
 		}
 		return
 
@@ -568,7 +633,7 @@ func (view *viewData) htmlProperties(self View, buffer *strings.Builder) {
 }
 
 func (view *viewData) htmlDisabledProperties(self View, buffer *strings.Builder) {
-	if IsDisabled(self) {
+	if IsDisabled(self, "") {
 		buffer.WriteString(` data-disabled="1"`)
 	} else {
 		buffer.WriteString(` data-disabled="0"`)
@@ -583,7 +648,7 @@ func viewHTML(view View, buffer *strings.Builder) {
 	buffer.WriteString(view.htmlID())
 	buffer.WriteRune('"')
 
-	disabled := IsDisabled(view)
+	disabled := IsDisabled(view, "")
 
 	if cls := view.htmlClass(disabled); cls != "" {
 		buffer.WriteString(` class="`)
@@ -660,7 +725,7 @@ func (view *viewData) handleCommand(self View, command string, data DataObject)
 	switch command {
 
 	case KeyDownEvent, KeyUpEvent:
-		if !IsDisabled(self) {
+		if !IsDisabled(self, "") {
 			handleKeyEvents(self, command, data)
 		}
 
@@ -767,13 +832,10 @@ func (view *viewData) String() string {
 	return writer.finish()
 }
 
-// IsDisabled returns "true" if the view is disabled
+func (view *viewData) SetChangeListener(tag string, listener func(View, string)) {
-func IsDisabled(view View) bool {
+	if listener == nil {
-	if disabled, _ := boolProperty(view, Disabled, view.Session()); disabled {
+		delete(view.changeListener, tag)
-		return true
+	} else {
+		view.changeListener[tag] = listener
 	}
-	if parent := view.Parent(); parent != nil {
-		return IsDisabled(parent)
-	}
-	return false
 }

viewUtils.go

@@ -4,7 +4,13 @@ package rui
 // The type of return value depends on the property.
 // If the subview don't exists or the property is not set then nil is returned.
 func Get(rootView View, viewID, tag string) interface{} {
-	if view := ViewByID(rootView, viewID); view != nil {
+	var view View
+	if viewID != "" {
+		view = ViewByID(rootView, viewID)
+	} else {
+		view = rootView
+	}
+	if view != nil {
 		return view.Get(tag)
 	}
 	return nil
@@ -14,12 +20,29 @@ func Get(rootView View, viewID, tag string) interface{} {
 // true - success,
 // false - error (incompatible type or invalid format of a string value, see AppLog).
 func Set(rootView View, viewID, tag string, value interface{}) bool {
-	if view := ViewByID(rootView, viewID); view != nil {
+	var view View
+	if viewID != "" {
+		view = ViewByID(rootView, viewID)
+	} else {
+		view = rootView
+	}
+	if view != nil {
 		return view.Set(tag, value)
 	}
 	return false
 }
 
+// SetChangeListener sets a listener for changing a subview property value.
+// If the second argument (subviewID) is "" then a listener for the first argument (view) is set
+func SetChangeListener(view View, viewID, tag string, listener func(View, string)) {
+	if viewID != "" {
+		view = ViewByID(view, viewID)
+	}
+	if view != nil {
+		view.SetChangeListener(tag, listener)
+	}
+}
+
 // SetParams sets properties with name "tag" of the "rootView" subview. Result:
 // true - all properties were set successful,
 // false - error (incompatible type or invalid format of a string value, see AppLog).
@@ -36,6 +59,22 @@ func SetParams(rootView View, viewID string, params Params) bool {
 	return result
 }
 
+// IsDisabled returns "true" if the subview is disabled
+// If the second argument (subviewID) is "" then a state of the first argument (view) is returned
+func IsDisabled(view View, subviewID string) bool {
+	if subviewID != "" {
+		view = ViewByID(view, subviewID)
+	}
+
+	if disabled, _ := boolProperty(view, Disabled, view.Session()); disabled {
+		return true
+	}
+	if parent := view.Parent(); parent != nil {
+		return IsDisabled(parent, "")
+	}
+	return false
+}
+
 // GetSemantics returns the subview semantics.  Valid semantics values are
 // DefaultSemantics (0), ArticleSemantics (1), SectionSemantics (2), AsideSemantics (3),
 // HeaderSemantics (4), MainSemantics (5), FooterSemantics (6), NavigationSemantics (7),
@@ -926,7 +965,7 @@ func valueFromStyle(view View, tag string) (string, bool) {
 		return "", false
 	}
 
-	if IsDisabled(view) {
+	if IsDisabled(view, "") {
 		if value, ok := getValue(StyleDisabled); ok {
 			return value, true
 		}

viewsContainer.go

@@ -39,16 +39,6 @@ func (container *viewsContainerData) setParentID(parentID string) {
 	}
 }
 
-// SetDisabled set the View disabled state
-func (container *viewsContainerData) SetDisabled(disabled bool) {
-	container.viewData.Set(Disabled, disabled)
-	if container.views != nil {
-		for _, view := range container.views {
-			view.Set(Disabled, disabled)
-		}
-	}
-}
-
 // Views return a list of child views
 func (container *viewsContainerData) Views() []View {
 	if container.views == nil {
@@ -68,6 +58,7 @@ func (container *viewsContainerData) Append(view View) {
 			container.views = append(container.views, view)
 		}
 		updateInnerHTML(container.htmlID(), container.session)
+		container.propertyChangedEvent(Content)
 	}
 }
 
@@ -81,10 +72,12 @@ func (container *viewsContainerData) Insert(view View, index uint) {
 			view.setParentID(htmlID)
 			container.views = append(container.views[:index], append([]View{view}, container.views[index:]...)...)
 			updateInnerHTML(container.htmlID(), container.session)
+			container.propertyChangedEvent(Content)
 		} else {
 			view.setParentID(htmlID)
 			container.views = append([]View{view}, container.views...)
 			updateInnerHTML(container.htmlID(), container.session)
+			container.propertyChangedEvent(Content)
 		}
 	}
 }
@@ -112,6 +105,7 @@ func (container *viewsContainerData) RemoveView(index uint) View {
 
 	view.setParentID("")
 	updateInnerHTML(container.htmlID(), container.session)
+	container.propertyChangedEvent(Content)
 	return view
 }
 
@@ -151,6 +145,18 @@ func (container *viewsContainerData) remove(tag string) {
 			container.views = []View{}
 			updateInnerHTML(container.htmlID(), container.Session())
 		}
+		container.propertyChangedEvent(Content)
+
+	case Disabled:
+		if _, ok := container.properties[Disabled]; ok {
+			delete(container.properties, Disabled)
+			if container.views != nil {
+				for _, view := range container.views {
+					view.Remove(Disabled)
+				}
+			}
+			container.propertyChangedEvent(tag)
+		}
 
 	default:
 		container.viewData.remove(tag)
@@ -167,7 +173,27 @@ func (container *viewsContainerData) set(tag string, value interface{}) bool {
 		return true
 	}
 
-	if tag != Content {
+	switch tag {
+	case Content:
+		// do nothing
+
+	case Disabled:
+		oldDisabled := IsDisabled(container, "")
+		if container.viewData.Set(Disabled, value) {
+			disabled := IsDisabled(container, "")
+			if oldDisabled != disabled {
+				if container.views != nil {
+					for _, view := range container.views {
+						view.Set(Disabled, disabled)
+					}
+				}
+			}
+			container.propertyChangedEvent(tag)
+			return true
+		}
+		return false
+
+	default:
 		return container.viewData.set(tag, value)
 	}
 
@@ -239,6 +265,8 @@ func (container *viewsContainerData) set(tag string, value interface{}) bool {
 	if container.created {
 		updateInnerHTML(htmlID, container.session)
 	}
+
+	container.propertyChangedEvent(Content)
 	return true
 }