Way to detect if window is dragged?

OK so I checked out Indiepath's code and all it does is prevent the user from dragging the window in DirectX and OpenGL. I'd like to allow users to drag and either not freeze program execution, or detect when a drag has occured and ended to reset the game timer to avoid big skips. Anyone done this sort of thing before?

Hmm idea: could monitor the x and y coords of the window and do this before the timing loop starts and when changed reset the timer! This still won't prevent the graphics window from "smearing" horribly as the user drags the window around.

Thanks.