Re: How to enable "enter-notify-event" for a GtkImage ?

[Arto Karppinen <exeonical mail suomi net>]

From http://library.gnome.org/devel/gtk/2.11/GtkEventBox.html:

GtkEventBox — A widget used to catch events for widgets which do not 
have their own window

As far as i understand how Gtk works, it does not create x windows for 
all widgets for performance reasons. Because events are tracked per x 
windows, a widget without x window cannot catch events. And because 
GtkImage does not need events by default, it does not need to have x window.

I have stumbled on this before and my understanding is that this is the 
way it is meant to be.


Gregory Hosler wrote:
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> Hi all,
>
> on the gtk_widget devhelp page, there is dome documentation about 
> signals common to all
> widgets. supposedly.
>
> I have a gtk_image, and i'd like to receive enter/leave notifications.
>
> I have enabled GDK_ENTER_NOTIFY_MASK | GDK_LEAVE_NOTIFY_MASK (as near 
> as I can tell) on
> the widget (gtk_widget_add_events), and my signal handler just isn't 
> firing...
>
> If I instead enable the NOTIFY_MASK's on an EventBox, then the signal 
> handler see's the
> signals.
>
> As a proof of concept, I took the paned.c example from the gtk+ 
> examples, and modified it
> (attached) (you'll need to supply your own image :) Anyway, if I 
> change the
> g_signal_connect's and the gtk_widget_add_events to the eboxprev (a 
> GtkEventBox), then I
> get the interrupts I want. But the problem w/ that approach is that 
> the event box covers
> an area greater than the image. I really only want enter/leave on the 
> image.
>
> I know that if I surround the image with an event box, and then 
> surround that with a tight
> box (doesn't give extra space to children), with enough layers between 
> the image and the
> scroll window, I can get what I want.
>
> But it seems to me that somehow I ought to be able to trigger 
> enter/leave events on the
> image itself. Or can not that be done ?
>
> - -Greg
>
> (p.s. I do note the disclaimer surrounding the 
> enter-notify-event/leave-notify-event's. It
> says "This signal will be sent to the grab widget if there is one." I 
> suppose the issue is
> that the GtkImage isn't "grabbing" the focus, yes ? any way around that ?
>
> - --
> +---------------------------------------------------------------------+
>
> Please also check the log file at "/dev/null" for additional information.
> (from /var/log/Xorg.setup.log)
>
> | Greg Hosler ghosler redhat com |
> +---------------------------------------------------------------------+
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--
Arto Karppinen
------------------------------
arto karppinen iki fi