Frame Levels

[markushe]

I created some art frames for my interface by

• creating a new ArtFrameType
• giving it a base frame and texture
• putting the art frame in a window object with a "frame:none"

Everything works fine except that I cannot get my art frame to show under some other addon frames.
I set everything to background (texture, Layout -> frame level, and in the desktop editor). Still they are always on top.

Is there anything I'm missing? Like somewhere where I can adjust the frame level?