Re: Question about GtkButton->event_window.

[Tristan Van Berkom <vantr touchtunes com>]

Tom Liu wrote:
> I check the source code of GtkButton, Looks the GtkButton create a
> GdkWindow called event_window. and  GtkButton->event_window coves the
> GtkWidget->window. But When expose event comes, they paint the button on
> the GtkWidget->window. How can the button's images show up?
>
>  
>
> Why the GtkButton don't use the GtkWidget->window as it's own GdkWindow?

I cant tell you *exactly* but here's an educated guess:

   (GTK_WIDGET_FLAGS(GTK_WIDGET(button)) & GTK_NO_WINDOW)

is true, so a button will draw to the widget->window (which belongs
to the parent), but since the GdkWindow (and effectivly the X
window) widget->window is bigger than the button, an "event_window"
is used to trap X's "enter-notify"/"leave-notify" in order to
implement prelight states and not execute extra code when the parent
window recieves mouse-overs.


Maykazecents ?

Cheers,
             -Tristan