Keyboard Event Processing

Keyboard events are sent by the Main Loop to the Application class for processing. The keyboard events are sent exclusively to the current Toplevel, this being either the default that is created when you call Application.Init, or one that you created an passed to Application.Run(Toplevel).

Flow

Keystrokes are first processes as hotkeys, then as regular keys, and there is a final cold post-processing event that is invoked if no view processed the key.

HotKey Processing

Events are first send to all views as a "HotKey", this means that the View.ProcessHotKey method is invoked on the current toplevel, which in turns propagates this to all the views in the hierarchy. If any view decides to process the event, no further processing takes place.

This is how hotkeys for buttons are implemented. For example, the keystroke "Alt-A" is handled by Buttons that have a hot-letter "A" to activate the button.

Regular Processing

Unlike the hotkey processing, the regular processing is only sent to the currently focused view in the focus chain.

The regular key processing is only invoked if no hotkey was caught.

Cold-key Processing

This stage only is executed if the focused view did not process the event, and is broadcast to all the views in the Toplevel.

This method can be overwritten by views that want to provide accelerator functionality (Alt-key for example), but without interefering with normal ProcessKey behavior.