SubMenuItem.IHandler

Remarks: Some platforms may use this to identify controls (e.g. web)

Remarks: Some platforms (e.g. OS X) will not show an image by default, but can be enabled using the handler implementation via styles.

Remarks: This is used primarily when creating menu items for system commands that the platform returns via MenuBar.SystemCommands.

Remarks: Most events are late bound by this method. Instead of wiring all events, this will be called with an event string that is defined by the control. This is called automatically when attaching to events, but must be called manually when users of the control only override the event's On... method.

Remarks: This gets called automatically after the control is constructed and the Widget.IHandler.Widget and Widget.Platform properties are set. When the handler has specialized construction methods, then the AutoInitializeAttribute can be used to disable automatic initialization. In this case, it is the responsibility of the subclass to call Widget.Initialize()

Remarks: Only reached for events whose remove accessor uses PropertyStore.RemoveHandlerEvent(string, Delegate), and only for events that were attached because something subscribed to them. An event attached because the widget overrides its On[Event] method is never detached, since it has to keep firing regardless. Most events stay attached for the life of the widget, which costs nothing. Detaching is worth wiring up for the few that hold onto something expensive or process wide while they are attached, such as a system wide hook. Handlers deriving from WidgetHandler<TWidget> get an implementation of this that dispatches to WidgetHandler<TWidget>.DetachEvent(string), which is what to override.