I'm a newbie, so perhaps I've missed a shortcut key somewhere (if so please let me know), but if it doesn't already exist please could you provide a way to lock the aspect ratio of the crop box while cropping an image? I want my slides to fill a 1024x768 projector screen without any black bars, but using a calculator to work out the correct aspect ratio of each crop in pixels is a REAL PAIN! If you could either select an aspect ratio (e.g. 4:3 or 16:9 or "custom") or just enter the dimensions of the crop you want e.g. 800x600 and then hold down shift or ctrl or something while you drag the handles to maintain the aspect ratio of the crop box that would be a HUGE HELP. Thanks, and apologies if I've missed this feature somewhere.