[gtk/matthiasc/for-master] x11: Fix getting the primary monitor

[Matthias Clasen <matthiasc src gnome org>]

commit 85318441ed4c5adbb7081c42ca6fcb06fea9340a
Author: Matthias Clasen <mclasen redhat com>
Date:   Sat Aug 8 10:17:06 2020 -0400

    x11: Fix getting the primary monitor
    
    Actually return the primary monitor.
    
    Fixes: #3038

 gdk/x11/gdkdisplay-x11.c | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)
---
diff --git a/gdk/x11/gdkdisplay-x11.c b/gdk/x11/gdkdisplay-x11.c
index 414d6dc63e..269ae28829 100644
--- a/gdk/x11/gdkdisplay-x11.c
+++ b/gdk/x11/gdkdisplay-x11.c
@@ -2859,15 +2859,14 @@ gdk_x11_display_get_primary_monitor (GdkDisplay *display)
   GdkX11Display *self = GDK_X11_DISPLAY (display);
   GdkMonitor *monitor;
 
-  if (0 <= self->primary_monitor)
-    return NULL;
-
   monitor = g_list_model_get_item (G_LIST_MODEL (self->monitors), self->primary_monitor);
   if (monitor == NULL)
-    return NULL;
+    monitor = g_list_model_get_item (G_LIST_MODEL (self->monitors), 0);
 
   /* because g_list_model_get_item() returns a ref */
-  g_object_unref (monitor);
+  if (monitor)
+    g_object_unref (monitor);
+
   return monitor;
 }