There are 2 features from other apps that I think are worth considering adding to Artstudio Pro.
The first is a dedicated Rotation Handle for transformations. Here is a video showing it from Affinity Designer.
https://youtu.be/ugC4f8cMrhQA dedicated move Handle might also be a good idea, since sometimes I want to stay zoomed out and the controls are to close together to easily move and rotate without switching to those modes.
Second is from Paintstorm Pro. They call it "Disable transformation", but really it's just manipulating the transformation box so that you can tranform in a way that easier to work with.
https://youtu.be/YMGDgJYeGo8This was extremely useful for me in the past when I needed to make a wall texture from a photo where the wall was in perspective and at an angle. This feature did it in seconds, when the normal transform tool would have taken many attempts of trial and error.
Edit: Here is a better example of Disable Transformation.
https://youtu.be/de-nrkLqsvwThanks for your consideration.