[gtk+] Fix up the fullscreen_on_monitor support

[Matthias Clasen <matthiasc src gnome org>]

commit 338534fb8d3d2f9749ada3ec3d69ddf88df6e911
Author: Matthias Clasen <mclasen redhat com>
Date:   Fri Nov 4 12:41:51 2016 -0400

    Fix up the fullscreen_on_monitor support
    
    I didn't pay attention, and forgot to port this code to the
    new monitor apis.

 gdk/x11/gdkwindow-x11.c |    4 +++-
 1 files changed, 3 insertions(+), 1 deletions(-)
---
diff --git a/gdk/x11/gdkwindow-x11.c b/gdk/x11/gdkwindow-x11.c
index 9d37eb1..19f8bcf 100644
--- a/gdk/x11/gdkwindow-x11.c
+++ b/gdk/x11/gdkwindow-x11.c
@@ -3960,13 +3960,15 @@ static void
 gdk_x11_window_fullscreen_on_monitor (GdkWindow *window,
                                       gint       monitor)
 {
+  GdkMonitor *m;
   GdkRectangle monitor_geom;
 
   if (GDK_WINDOW_DESTROYED (window) ||
       !WINDOW_IS_TOPLEVEL_OR_FOREIGN (window))
     return;
 
-  gdk_screen_get_monitor_geometry (GDK_WINDOW_SCREEN (window), monitor, &monitor_geom);
+  m = gdk_display_get_monitor (gdk_window_get_display (window), monitor);
+  gdk_monitor_get_geometry (m, &monitor_geom);
   gdk_window_move (window, monitor_geom.x, monitor_geom.y);
 
   gdk_window_set_fullscreen_mode (window, GDK_FULLSCREEN_ON_CURRENT_MONITOR);