Here is the thread with my feature request: Enhanced "paste on" block .
And another thread where we discuss my initial task: to have an instrument able to make parts of a sprite transparent: Paste a Sprite on another Sprite - #6 by pavelbel
So the CUT FROM block is a best and fastest way to cut off parts of the sprite using another sprite as a stencil.
I've asked for more, but Jens decided to add just that 