I've been playing with NEM and Win32::GUI::Graphic objects and there seems to be some differences between the NEM and OEM events (NEM does not fire _LButtonDown,_RButtonDown for example). The Win32::GUI::Graphic NEM is handled via NEM_ChildMsgLoop and in OEM via InteractiveGraphicMsgLoop (when the Graphic object has the interactive flag). Another problem I've noticed is that for some reason, the WM_ERASEBKGND is fired in NEM, which causes the background of the image to be redrawn (causing a flicker)...