DllCall is great. But it can be tricky to use. Here are some syntax notes geared towards using the Windows API. When you manage to get DllCall to work with a new api then please post the syntax you used and the MSDN API syntax so that others may benefit. I'll merge all the posts into this one. Windows API All the Windows API details you need can be found by searching at MSDN Library Common Datatypes AutoIt has a single datatype - the variant. A variant can hold HWNDs (window handles), in