[virt-tools-list] [PATCH virt-viewer] Fullscreen displays on wrong monitors in Wayland

[Jonathon Jongsma]

On Mon, 2018-10-15 at 10:42 +0200, Christophe Fergeau wrote:
> On Fri, Oct 12, 2018 at 02:51:19PM -0500, Jonathon Jongsma wrote:
> > In fullscreen mode, we attempt to enable a guest display for each
> > client
> > monitor and then place a fullscreen window for each display on the
> > appropriate monitor. Previously, we were using gtk_window_move() to
> > move
> > the window to the proper monitor, and then calling
> > gtk_window_fullscreen() to enter fullscreen mode on that monitor.
> > However, under wayland, gtk_window_move() no longer has any effect
> > for
> > toplevel windows, so all displays were showing up on top of
> > eachother on
> > the same client monitor.
> > 
> > Fortunately, Gtk+ 3.18 added a new
> > gtk_window_fullscreen_on_monitor()
> > API that works on Wayland. In theory this allows us to remove the
> > call
> > to gtk_window_move() from the code. But to avoid potentially
> > changing
> > behavior on xorg or older systems, I left the existing logic.
> 
> Any plans to remove the gtk_window_move() call later on? Or do you
> think
> we should keep it forever? Apart from that,

It's hard to say. The thing we gain by moving and then fullscreening is
that when that window gets un-fullscreened, it stays on the same
monitor that it was fullscreened on. On the other hand, if you just
call gtk_window_fullscreen_on_monitor() without moving the window to
that monitor first, when that window gets un-fullscreened, it can be
restored to a different monitor (e.g.the one that had the active focus
when the application was launched). As far as I can tell, there's
nothing we can do to prevent this on Wayland. 

Eventually this will become a moot point since the future is wayland
and gtk_window_move() does nothing on wayland. But until then there is
at least some minor benefit to leaving the _move() call in the code for
those still running under X.

Jonathon

> 
> Acked-by: Christophe Fergeau <cfergeau at redhat.com>
> 
> Christophe