I thought of something that would be really useful when it comes to coloring lineart. In the tool options docker for the fill bucket there's an option to limit fill to current layer. I'd like to propose another checkbox to limit fill to selected layers. In this way you can select a layer (or layers) and be able to fill on a different layer without any other layers being in the way. I'm sure there could be other potential uses that I haven't thought of before, but I hope that I explained it well enough!
That does sound interesting... I wonder how feasible it is though.
It is already implemented as filling using color labeled layers as a reference. Please check out Krita 4.3.0 release notes to see details. It's not "selected layers" but I guess it's not only solving the issue you're having, but also solving it in a better way - you can just mark all lineart layers with one color and use it at any time later. So, should we close this wish?
Yes, let's close it. Ramskull, if this isn't what you meant, please reopen.