[metacity] display: Don't grab transient's parent unconditionally

[Alberts Muktupāvels <muktupavels src gnome org>]

commit b79d3b8c2768243d35cb27e3e825790ef1c6e409
Author: Florian Müllner <fmuellner gnome org>
Date:   Fri May 2 12:20:32 2014 +0200

    display: Don't grab transient's parent unconditionally
    
    Since previous commit, move operations are always performed for
    the (toplevel) parent of all transient, which is just plain silly
    if the dialog is not actually attached to its parent (either because
    the dialog is not modal or the setting is disabled).

 src/core/display.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)
---
diff --git a/src/core/display.c b/src/core/display.c
index 5cf79af..b11cecc 100644
--- a/src/core/display.c
+++ b/src/core/display.c
@@ -3325,7 +3325,8 @@ meta_display_begin_grab_op (MetaDisplay *display,
   /* If window is a modal dialog attached to its parent,
    * grab the parent instead for moving.
    */
-  if (meta_grab_op_is_moving (op))
+  if (window && meta_window_is_attached_dialog (window) &&
+      meta_grab_op_is_moving (op))
     grab_window = get_toplevel_transient_for (window);
 
   /* FIXME: