[nautilus] dnd: only allow the desktop as target for special desktop items

[Cosimo Cecchi <cosimoc src gnome org>]

commit e0b864eed48c71b64e177507caa435df6ccba158
Author: Cosimo Cecchi <cosimoc gnome org>
Date:   Wed Apr 10 15:38:45 2013 -0400

    dnd: only allow the desktop as target for special desktop items
    
    When a special desktop item (Home, Trash and the volumes shortcut) is
    dragged, only the desktop itself is a valid destination target.

 libnautilus-private/nautilus-dnd.c |    7 +++++++
 1 files changed, 7 insertions(+), 0 deletions(-)
---
diff --git a/libnautilus-private/nautilus-dnd.c b/libnautilus-private/nautilus-dnd.c
index 5c175f2..dcb990f 100644
--- a/libnautilus-private/nautilus-dnd.c
+++ b/libnautilus-private/nautilus-dnd.c
@@ -461,6 +461,13 @@ nautilus_drag_default_drop_action_for_icons (GdkDragContext *context,
        dropped_file = ((NautilusDragSelectionItem *)items->data)->file;
        target_file = nautilus_file_get_existing_by_uri (target_uri_string);
 
+       if (eel_uri_is_desktop (dropped_uri) &&
+           !eel_uri_is_desktop (target_uri_string)) {
+               /* Desktop items only move on the desktop */
+               *action = 0;
+               return;
+       }
+
        /*
         * Check for trash URI.  We do a find_directory for any Trash directory.
         * Passing 0 permissions as gnome-vfs would override the permissions