1. Is there a reason why DrawingCanvas can not be rotated? I'm guessing it will mess up snapshot functions. But one of the usages of DrawingCanvas is to create "skins" for objects and not being able to rotate it is a big limitation.. Imagine a jigsaw puzzle where pieces can be rotated - this was possible in C2 with Paster/Canvas addon, but there is no way of doing it with DrawingCanvas.
2. How do I fill an area on DrawingCanvas with transparent color overwriting existing pixels? For example, I need to paste an image onto the canvas, and then make a hole in it. "Fill" actions with color rgba(0,0,0,0) has no effect. The only way I can think of is with blend modes - draw the hole on another canvas, use it as a mask, paste on the first canvas, but it's not very convenient.