[gnome-flashback] shell: avoid deprecated gdk_screen_get_n_monitors

[Alberts Muktupāvels <muktupavels src gnome org>]

commit faa938990f137724a8aa178d4e2ad52fc6de2451
Author: Alberts Muktupāvels <alberts muktupavels gmail com>
Date:   Thu Sep 28 19:16:19 2017 +0300

    shell: avoid deprecated gdk_screen_get_n_monitors

 gnome-flashback/libshell/flashback-osd.c |    5 ++++-
 1 files changed, 4 insertions(+), 1 deletions(-)
---
diff --git a/gnome-flashback/libshell/flashback-osd.c b/gnome-flashback/libshell/flashback-osd.c
index 0f50aee..cbad3a2 100644
--- a/gnome-flashback/libshell/flashback-osd.c
+++ b/gnome-flashback/libshell/flashback-osd.c
@@ -36,11 +36,14 @@ monitors_changed (GdkScreen *screen,
                   gpointer   user_data)
 {
   FlashbackOsd *osd;
+  GdkDisplay *display;
   gint n_monitors;
   gint i;
 
   osd = FLASHBACK_OSD (user_data);
-  n_monitors = gdk_screen_get_n_monitors (screen);
+
+  display = gdk_display_get_default ();
+  n_monitors = gdk_display_get_n_monitors (display);
 
   if (osd->windows != NULL)
     {