titlebar: call property hook on visible, not need_arrange

Signed-off-by: Julien Danjou <julien@danjou.info>

lib/awful/layout/init.lua.in

@@ -115,7 +115,8 @@ hooks.property.register(function (obj, prop)
             end
         end
     elseif objtype == "wibox" then
-        if prop == "screen" then
+        if prop == "screen"
+            or prop == "visible" then
             on_arrange(obj.screen)
         end
     end

titlebar.c

@@ -304,7 +304,7 @@ titlebar_set_visible(wibox_t *t, bool visible)
         else
             titlebar_ban(t);
 
-        t->screen->need_arrange = true;
+        hook_property(wibox, t, "visible");
         client_stack();
     }
 }