Andrew de Quincey adq_dvb@lidskialf.net writes:
OK, I'll keep looking. I've printed out the coordinates I get in the tracking loop. As soon as the popup menu is displayed, they are immediately "off" by the position of the menu on the top of the screen. Its fine on menus without popups.
Probably the app is messing with the mouse capture.
Out of interest, why do you specifically have to use lParam? Since it is (supposed to be) in screen coordinates, surely GetCursorPos() has to return the same values?
Some programs want to modify menu behavior by changing the message parameters, or even sending new messages that don't correspond to real events. And even if this wasn't the case, using GetCursorPos() is wrong since it returns the current mouse position, not the position at the time the message was generated.