[gtk+] Add a drag-end callback

[Matthias Clasen <matthiasc src gnome org>]

commit a8a33b71e4fb3077c5b7cdd65f248515a1c525ea
Author: Matthias Clasen <mclasen redhat com>
Date:   Fri Dec 11 10:50:25 2015 -0500

    Add a drag-end callback
    
    This will be helpful in figuring out life-cycle issues
    with icon widgets.

 tests/testdnd2.c |   13 +++++++++++++
 1 files changed, 13 insertions(+), 0 deletions(-)
---
diff --git a/tests/testdnd2.c b/tests/testdnd2.c
index eb4c174..0447dc0 100644
--- a/tests/testdnd2.c
+++ b/tests/testdnd2.c
@@ -199,6 +199,18 @@ spinner_drag_begin (GtkWidget      *widget,
                           "active",  TRUE,
                           NULL);
   gtk_drag_set_icon_widget (context, spinner, 0, 0);
+  g_object_set_data (G_OBJECT (context), "spinner", spinner);
+}
+
+static void
+spinner_drag_end (GtkWidget      *widget,
+                  GdkDragContext *context,
+                  gpointer        data)
+{
+  GtkWidget *spinner;
+
+  spinner = g_object_get_data (G_OBJECT (context), "spinner");
+  gtk_widget_destroy (spinner);
 }
 
 void
@@ -225,6 +237,7 @@ make_spinner (void)
   gtk_drag_source_add_text_targets (ebox);
 
   g_signal_connect (ebox, "drag-begin", G_CALLBACK (spinner_drag_begin), spinner);
+  g_signal_connect (ebox, "drag-end", G_CALLBACK (spinner_drag_end), spinner);
   g_signal_connect (ebox, "drag-data-get", G_CALLBACK (spinner_drag_data_get), spinner);
 
   gtk_container_add (GTK_CONTAINER (ebox), spinner);