I am writing a windows shell and i am looking for a way to keep a window behind all open windows (even when it is active)

Currently, i am subclassing the wm_activateapp message and using setwindowpos to move the window to the bottom, but this is not as smooth as i want it to be.

I'm just wondering how windows explorer does it so i can finish my shell.

I've looked through the MSDN Win32 SDK looking for a window style that does this. I've looked for flags for setwindowpos. I've also looked for a windows message. No luck what-so-ever.

The subclass method is the only thing i can think of, but it still remains in front of explorer, so i know that the subclassing method is not the same method that explorer uses.