Check whether desktop is shown using _NET_SHOWING_DESKTOP X11 Exten…

…ded Window Manager Hints property.

To correctly reflect the desktop showing state in the UI, the current state needs to be
read from X11 properties set by the window manager. Otherwise the UI may not always
be updated when desktop showing state is changed by other applications.

plugins/wincmd.c

@@ -136,6 +136,7 @@ static gboolean wincmd_button_clicked(GtkWidget * widget, GdkEventButton * event
          * Otherwise, fall back to iconifying windows individually. */
         if (gdk_x11_screen_supports_net_wm_hint(screen, atom))
         {
+
 	    wc->toggle_state = get_net_showing_desktop();
 
             int showing_desktop = ((( ! wc->toggle_preference) || ( ! wc->toggle_state)) ? 1 : 0);