[gtk+/gtk-3-20] dnd: Fix lifecycle issues with widgets as drag icons

[Matthias Clasen <matthiasc src gnome org>]

commit 7054b0ccff7c977ad51c1f4ae13848b4704c246e
Author: Matthias Clasen <mclasen redhat com>
Date:   Tue Apr 26 20:35:25 2016 -0400

    dnd: Fix lifecycle issues with widgets as drag icons
    
    The documentation clearly says that the widget is not destroyed,
    but we were in fact failing to keep it alive, since it was still
    a child or the icon_window when we destroy that. Fix this by
    reparenting the icon_widget out before. Also, deal with the
    possibility that the application might destroy the widget
    halfway through, for whatever reason.

 gtk/gtkdnd.c |   13 +++++++++++++
 1 files changed, 13 insertions(+), 0 deletions(-)
---
diff --git a/gtk/gtkdnd.c b/gtk/gtkdnd.c
index 48be48c..a055c30 100644
--- a/gtk/gtkdnd.c
+++ b/gtk/gtkdnd.c
@@ -2501,6 +2501,13 @@ gtk_drag_begin (GtkWidget     *widget,
 }
 
 static void
+icon_widget_destroyed (GtkWidget         *widget,
+                       GtkDragSourceInfo *info)
+{
+  g_clear_object (&info->icon_widget);
+}
+
+static void
 gtk_drag_set_icon_widget_internal (GdkDragContext *context,
                                    GtkWidget      *widget,
                                    gint            hot_x,
@@ -2530,6 +2537,8 @@ gtk_drag_set_icon_widget_internal (GdkDragContext *context,
   if (!widget)
     goto out;
 
+  g_signal_connect (widget, "destroy", G_CALLBACK (icon_widget_destroyed), info);
+
   gdk_drag_context_set_hotspot (context, hot_x, hot_y);
 
   if (!info->icon_window)
@@ -3204,11 +3213,15 @@ gtk_drag_remove_icon (GtkDragSourceInfo *info)
       widget = info->icon_widget;
       info->icon_widget = NULL;
 
+      g_signal_handlers_disconnect_by_func (widget, icon_widget_destroyed, info);
+
       gtk_widget_hide (widget);
       gtk_widget_set_opacity (widget, 1.0);
 
       if (info->destroy_icon)
         gtk_widget_destroy (widget);
+      else
+        gtk_container_remove (GTK_CONTAINER (info->icon_window), widget);
 
       g_object_unref (widget);
     }