Is window client area transparency possible?

Is it possible to create a main window such that its client area is completely transparent? I'm on X11, using Qt 4.4.1, and am running under an older (almost ancient) X11 window manager that does not support compositing. I guess what I am looking for is a way to basically disable drawing of the window client area, but still be able to draw non-transparently over it. I have experimented with WA_NoSystemBackground and WA_OpaquePaintEvent with no success. I realize this is a tall order, but I was wondering if anyone knows of a trick or setting to allow this to happen.

Thanks in advance.