[gtk+/gtk-3-22] gdkscreen-x11: Fix screen and monitor size calculation

[Matthias Clasen <matthiasc src gnome org>]

commit cb535626590b9493e5ea1ee14d7536034df2ab26
Author: Jan Alexander Steffens (heftig) <jan steffens gmail com>
Date:   Mon Oct 10 16:34:28 2016 +0200

    gdkscreen-x11: Fix screen and monitor size calculation
    
    The monitors are already in scaled pixels, so scaling again when retrieving
    the screen size is wrong.
    
    With GDK_SCALE unset, the initial monitor sizes are unscaled, and when the
    xsettings client sets a scale > 1, the monitor sizes should be updated.
    
    The end result is that the monitor sizes start out wrong, and get
    corrected on the first xrandr event, while the screen size starts out
    right and becomes wrong after the event.
    
    This patch fixes Firefox misplacing menus and popovers when the xrandr
    configuration changes while it is running.
    
    Fix for the X11 side of
    
    https://bugzilla.gnome.org/show_bug.cgi?id=772202

 gdk/x11/gdkscreen-x11.c |   16 ++++------------
 1 files changed, 4 insertions(+), 12 deletions(-)
---
diff --git a/gdk/x11/gdkscreen-x11.c b/gdk/x11/gdkscreen-x11.c
index 7738a47..28a43a6 100644
--- a/gdk/x11/gdkscreen-x11.c
+++ b/gdk/x11/gdkscreen-x11.c
@@ -49,6 +49,7 @@
 static void         gdk_x11_screen_dispose     (GObject                  *object);
 static void         gdk_x11_screen_finalize    (GObject                  *object);
 static void        init_randr_support         (GdkScreen         *screen);
+static void         process_monitors_change    (GdkScreen         *screen);
 
 enum
 {
@@ -82,13 +83,13 @@ gdk_x11_screen_get_display (GdkScreen *screen)
 gint
 gdk_x11_screen_get_width (GdkScreen *screen)
 {
-  return GDK_X11_SCREEN (screen)->width / GDK_X11_SCREEN (screen)->window_scale;
+  return GDK_X11_SCREEN (screen)->width;
 }
 
 gint
 gdk_x11_screen_get_height (GdkScreen *screen)
 {
-  return GDK_X11_SCREEN (screen)->height / GDK_X11_SCREEN (screen)->window_scale;
+  return GDK_X11_SCREEN (screen)->height;
 }
 
 static gint
@@ -906,10 +907,8 @@ void
 _gdk_x11_screen_set_window_scale (GdkX11Screen *x11_screen,
                                  gint          scale)
 {
-  GdkX11Display *x11_display = GDK_X11_DISPLAY (x11_screen->display);
   GList *toplevels, *l;
   GdkWindow *root;
-  int i;
 
   if (x11_screen->window_scale == scale)
     return;
@@ -928,14 +927,7 @@ _gdk_x11_screen_set_window_scale (GdkX11Screen *x11_screen,
       _gdk_x11_window_set_window_scale (window, scale);
     }
 
-  for (i = 0; i < x11_display->monitors->len; i++)
-    {
-      GdkMonitor *monitor = GDK_MONITOR (x11_display->monitors->pdata[i]);
-
-      gdk_monitor_set_scale_factor (monitor, scale);
-    }
-
-  g_signal_emit_by_name (GDK_SCREEN (x11_screen), "monitors-changed");
+  process_monitors_change (GDK_SCREEN (x11_screen));
 }
 
 /*