Re: GdkScreen size-changed and gdk_monitor_get_workarea problem

["Sebastian Geiger (Lanoxx)" <lanoxx gmx net>]

Dear Bastien,

thanks for the reply. I will attach a sample next time.

My App runs with the X11 backend.

I was able to resolve the issue yesterday, and found that it was not 
directly a Problem of GTK+.

The problem is, that the window manager computes the workarea 
asynchronosly, presumably its handled in a g_add_idle callback.
When I tried to use get_geometry instead of get_workarea I was always 
getting the correct values, but I specifically needed the workarea so 
that was not helping.

My solution was then to register a filter function with 
gdk_window_add_filter which listens for _NET_WORKAREA property changes 
and then queue a g_add_idle callback which handles the change.

I tested the behavior with mutter and metacity and both had the same 
problem.

I am not sure if this is by design, or a bug. However, I would like to 
suggest that we add a small note to the documentation of the 
monitor-changed signal and the size-change signal, stating that
values reported by gdk_monitor_get_workarea might arrive delayed.
Alternatively, fixing mutter and metacity would be my preferred solution 
but would probably be more work and I have not the necessary knowledge 
about mutter code to fix this myself.

Best Regards
Sebastian

On 07/11/18 20:08, Bastien Nocera wrote:
> On Tue, 2018-11-06 at 21:35 +0100, Sebastian Geiger (Lanoxx) wrote:
> > Hi Gtk developers,
> >
> > I am experiencing a wired issue and I am wondering if I am using the
> > API
> > in a wrong way of if there is a problem with Gtk.
>
> On Wayland or X11?
>
> <snip>
>
> > gdk_display_get_monitor_at_point and then gdk_monitor_get_workarea.
>
> IIRC, the latter function isn't implemented in Wayland.
>
> In the future, it would also probably be best if you could attach or
> copy/paste a minimal test case, so folks on the mailing-list can try
> your code, and see either if there are errors in the code, or those are
> really bugs (or missing functionality).
>
> Cheers