The render order by z

[shokinhan]

The window's widgets has marked by the depth of z. So the value of z is very smaller, and then the widget render earlier!
When I open the window, some icon show earlier and then show the background.

But I want to render the background earlier and then render other icon.
How to resolve the probleam?

[ArenMook]

Move the window forward by a large margin, such as -10.