Masking multiple layers at the same time

[rich2005]

For Gimp 2.8.x a layer mask created from either a selection or a channel for each layer is about as fast as anything.

Gimp 2.10 allows a mask on a layer group.

Depends on your distro but a linux appimage might work. Try the last 2.9.9 one from here

https://github.com/aferrero2707/gimp-appimage/releases/

Sort of works with my Kubuntu 16.04 except problem with adding python plugins which do not show. - still worth a try.