On Thu, 2003-10-16 at 22:56, David Bourguignon wrote:
> Hi all,
>
> I'm trying to get extension events information from a button widget. This is
> useful, for example, to know which input device caused the button to emit a
> "button_press_event" signal. To test this feature, I modified the
> scribble-xinput.c example given with the distribution by adding another signal
> handler before the "clicked" signal handler for the quit button:
>
> g_signal_connect (G_OBJECT (button), "button_press_event",
> G_CALLBACK (quit_button_press_event), NULL);
>
> and setting the events and extension events masks for the button:
>
> gtk_widget_set_events (button, GDK_BUTTON_PRESS_MASK);
> gtk_widget_set_extension_events (button, GDK_EXTENSION_EVENTS_CURSOR);
>
> I finally defined the following basic callback:
>
> static gint
> quit_button_press_event (GtkWidget *widget, GdkEventButton *event)
> {
> print_button_press (event->device);
> return FALSE;
> }
>
> After setting up devices, I used the drawing area with my tablet stylus, getting
> expected messages such as "Button press on device 'stylus'" from the drawing
> area "button_press_event" signal handler (see the original code). However, after
> clicking on the quit button to exit the program, I got only "Button press on
> device 'Core Pointer'" from the quit_button_press_event callback.
>
> According to this example, it seems that the quit button cannot be setup to emit
> extension events... Is it true or am I missing something?
Not all widgets honor gtk_widget_set_extension_events(). If you look at
the code for gtk_widget_realize(), you'll see how it is handled there.
This default realize() handler is inherited by GtkDrawingArea, but most
widgets aren't going to do anything with it.
(Generally, catching ::button-press-event on a widget like GtkButton
is discouraged, since by doing that you are assuming you know exactly
how GtkButton is going to handle button presses and safely override it.)
Regards,
Owen
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