Improvements for the Crop tool.

[Rafagd]

This is a feature Blender should have by default and for some reason doesn't, but I feel we could improve this just a little bit by adding two essential functionalities of any selection tool: Ctrl+LMB or Shift+LMB for "fixed ratio resize of the box", which could default to a square, and maybe some field to set a custom ratio if we wanted something else, like 4:3, 16:9...

I would gladly dive on the code to add it myself, but I'm kinda short on time, so I'm posting this issue just in case it is a problem that has been overlooked.

[Rokerekor]

Having the dimensions of the crop box displayed would be awesome too