shell: Do not remove input panel layer when locked

Do not remove the input panel layer from the layer list when the
shell is locked in hide_input_panels().

https://bugs.freedesktop.org/show_bug.cgi?id=56543

Signed-off-by: Jan Arne Petersen <jpetersen@openismus.com>

src/shell.c

@@ -2806,7 +2806,8 @@ hide_input_panels(struct wl_listener *listener, void *data)
 
 	shell->showing_input_panels = false;
 
-	wl_list_remove(&shell->input_panel_layer.link);
+	if (!shell->locked)
+		wl_list_remove(&shell->input_panel_layer.link);
 
 	wl_list_for_each_safe(surface, next,
 			      &shell->input_panel_layer.surface_list, layer_link)