it's not a bad idea to add it. we'd also have to add a 2nd step after selecting the region, where you 'confirmed' the capture with a keypress or mouse click or something though so you'd have time to position your mouse.
actually though i try to recommend that people just completely forget about selected region capture - surely the better approach is just capture whole screen and then after that, select and drop. basically same number of clicks and you can change your mind, etc.
