I am trying to clip photos to a specific aspect ratio (3 x 1) for the top banner of a website but can't find a way to lock the aspect ratio to that value. It only seems to be possible to lock it at the "current" value which is that of the original photo, or the fixed presets of 4:3, 3:2 or 16:9. Is there a work-around for this? The only other thing I have thought of is overlaying a rectangle of the right proportions and then "Intersect shapes", but it would be useful if I could actually use the clip tool.