[gtk+] GtkPopover: Don't ref NULL widgets

[Timm Bäder <baedert src gnome org>]

commit c28275f4ec1d02698336aea7cffd4aabaa1e61b0
Author: Timm Bäder <mail baedert org>
Date:   Sun May 3 12:19:18 2015 +0200

    GtkPopover: Don't ref NULL widgets
    
    gtk_window_get_default_widget returns NULL if the window does not have a
    default widget, so don't ref it in that case.

 gtk/gtkpopover.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)
---
diff --git a/gtk/gtkpopover.c b/gtk/gtkpopover.c
index 49d2fc2..5c9103e 100644
--- a/gtk/gtkpopover.c
+++ b/gtk/gtkpopover.c
@@ -582,7 +582,8 @@ gtk_popover_map (GtkWidget *widget)
   GtkPopoverPrivate *priv = GTK_POPOVER (widget)->priv;
 
   priv->prev_default = gtk_window_get_default_widget (priv->window);
-  g_object_ref (priv->prev_default);
+  if (priv->prev_default)
+    g_object_ref (priv->prev_default);
 
   GTK_WIDGET_CLASS (gtk_popover_parent_class)->map (widget);