@falktx @prokoudine @GIMP @inkscape

The base implementation is done and already works. TODO: details, workflow, integration to existing tools, saving/loading…
Similar state for vector layers (base implementation works but work to go from demo to releasable state).
I put a slowdown on these otherwise we'll never release GIMP 3.0. My "3.0.2" milestone means "main work done so it will likely be released very soon after 3.0.0 (otherwise we'd push 3.0.0 release a few more months down the road).