Remove _NET_WM_DESKTOP when client got no tags

EWMH says that "Window Managers MUST keep this property updated on all windows",
but doesn't say anything about clients which got no desktop at all. Removing the
property seems to be the best we could do.

Signed-off-by: Uli Schlachter <psychon@znc.in>
Signed-off-by: Julien Danjou <julien@danjou.info>

ewmh.c

@@ -444,6 +444,8 @@ ewmh_client_update_desktop(client_t *c)
                                 c->window, _NET_WM_DESKTOP, CARDINAL, 32, 1, &i);
             return;
         }
+    /* It doesn't have any tags, remove the property */
+    xcb_delete_property(globalconf.connection, c->window, _NET_WM_DESKTOP);
 }
 
 /** Update the client struts.