Hi, I'm experimenting with GHC as a platform for writing a Win32 GUI application, and I've hit what I think is a brick wall. The problem I think is with the lightweight thread implementation - Win32 calls can (and will) block the OS thread that makes the call, which blocks the entire system. Given that I'm wanting to write a network server with a Win32 GUI, this is obviously a Bad Thing. So, does any know if I missing some vital piece of information? I am using the following reduced test case, which I don't think is clueless. import Win32 import Concurrent endless:: Char -> IO () endless c = do { putChar c; endless c } main = do { task1; task2; endless 'b' } where task1 = forkIO ( do { messageBox nullHANDLE "Hey" "Yeah" mB_OK; return () } ) task2 = forkIO ( endless 'a' ) It does intersperse the 'a' and 'b' output nicely, but stops while the message box is on the screen. I'm not keen on writing a seperate GUI management thread in C++ and linking - the point is to do all of this in Haskell and write an application indistinguishable from a C++ GUI app e.g. imagine Simon Peyton Jones' sample webserver with a realtime GUI monitor. Thanks in advance for any pointers!