Pressing shift while dragging the cropping selection does nothing. Desired result: constrain the aspect ratio to square.
You mean the Crop Tool, not any of the selection tools, right?
I think so (it's been a month), but it would be great if Shift forced any selection-like tool to output a square shape.
Shift should conserve the actual aspect ratio of the crop/selection, not enforce a square shape... This is default photoshop like behaviour and everyone expects to work like that. So if I made a rectangle like crop area, pressing shift and dragging the middle/corner sliders should shrink/enlarge the crop area while keeping the aspect ratio of the initial selection.
There is a way to conserve the ratio by locking it in the Tool Options, but yes, using Shift either for squares or for conserving the ratio (possibly ctrl+Shift for a square?) would be nice.