So now that every other problem of mine is fixed, I was just wondering: I'm trying to make a message-handling function for WM_LBUTTONDOWN, but I don't know what parameters it should take - it says "fwFlags = wParam" in MSDEV's help, and also xPos and yPos are HIWORD/LOWORD of lParam. But what data types are fwFlags, xPos and yPos? And then, how could I separate the flags in fwFlags? (is there a macro or something, or is it guess and check?)