@navi @nikitonsky Yeah, it _will be_ pretty feasible. No compositor implements this yet, especially combining ext-screencopy-v1 with ext-foreign-toplevel-list.
And yeah, the only right solution here is to save it into a layered image to use in a layered image editor. If you don't save layers, then this kind of editing wouldn't be possible.
You can also use ext-foreign-toplevel-list to _name_ the layers themselves.
For tiling desktop, you can easily crop a single window, but that's about it.