I suggest that to constrain the angle by increments of 15° would be more useful. That would offer users the option of cutting by 15°, 30° 45°, 60°, or 75° as well as the current 90° increments.
Hi there
Here’s a feature from Photoshop that is absent from the Glyph window Contour Mode click transform rotate feature, the one that you activate by clicking on a shape twice, and then grabbing a corner:
15, 30, or 45 degree increments when holding the SHIFT key.
Right now you can rotate to any angle, it’s just not quantized.