Make a PtWindow always stay on top

This is for a new feature I am adding to an existing application, an onscreen virtual keypad.

I am trying to make a pop-up window always stay on top even if i click on a window which is visiable behind it. I have been looking through the flags and setting some like Ph_WM_TOFRONT, Ph_WM_FFRONT but nothing I have done so far will make the window always stay on top. The pop-up will open as the top most window though.