I would like to be able to remove the frame and pins on references or additional views, use the same keyboard shortcuts in additional views, and adjust or remove the clickable icons for options and such (replaced with keyboard modifier key and mouse combinations when the icon is turned off). Also, being able to change the shape of the reference window away from whatever is set by the image loaded would be nice, I might want to use it to functionally act as a cropped portion of that reference for compositional purposes.
If anyone else has some suggestions or requests that you would like to see on the UI of ArtRage, I strongly encourage adding to this thread to build upon these requests.