Not neccessarily. Since what you want to implement using Win32::API (with great difficulty I guess) is already present in Win32::GUI, why not use it? The only downside I can see is the overhead.

It is most likely possible to combine the main event loop in Tk with the one in Win32::GUI; Just call Win32::GUI::DoEvents() as often as possible from within Tk's idle event loop (whatever it is called, I don't know Tk that well).

/J