[gtk/matthiasc/for-master: 6/7] gtk-demo: Use proper drag icons in the dnd demo

[Matthias Clasen <matthiasc src gnome org>]

commit 028bccc18845f7de867cd98f3af3472dfc260084
Author: Matthias Clasen <mclasen redhat com>
Date:   Fri May 22 10:50:09 2020 -0400

    gtk-demo: Use proper drag icons in the dnd demo
    
    Use a widget paintable to make the drag icon appear
    in two places at once.

 demos/gtk-demo/dnd.c | 5 +++++
 1 file changed, 5 insertions(+)
---
diff --git a/demos/gtk-demo/dnd.c b/demos/gtk-demo/dnd.c
index 5510e61c6a..5d7e11273c 100644
--- a/demos/gtk-demo/dnd.c
+++ b/demos/gtk-demo/dnd.c
@@ -32,10 +32,15 @@ drag_begin (GtkDragSource *source,
 {
   GtkWidget *canvas;
   GtkWidget *item;
+  GdkPaintable *paintable;
 
   canvas = gtk_event_controller_get_widget (GTK_EVENT_CONTROLLER (source));
   item = g_object_get_data (G_OBJECT (canvas), "dragged-item");
 
+  paintable = gtk_widget_paintable_new (item);
+  gtk_drag_source_set_icon (source, paintable, 0, 0);
+  g_object_unref (paintable);
+
   gtk_widget_set_opacity (item, 0.5);
 }