Just like the title mentions, the addition to the layer docker is as follows:
And the added functionality is to move the selected layers at the top/bottom of the group player in one go. This is a first pass and better ideas are welcome.
As discussed via IRC, I've included only the svg dark/light icons that appear in the above image, but the compilation fails only with this. With the png files in the source code the compilation succeeds so advice on this is needed.
note
I removed the code that enabled/disabled the move up/down layer in the layer docker as well since it really is inconsistent as it only takes in account the "active node/layer", but the operation can be performed on multiple selected layers as well. Same goes for move to top/bottom of group layer so we either have to come up with a better solution for enabling/disabling these buttons or just not use it at all.