Hey Bjorn,
I’d like to select a group layer, then have the new multi-layer select/copy/paste operate on all the tile layers within the group. But the toolbar goes grey when I select a group, so it looks like it’s unimplemented. Are there plans? Can I file a request on github?
Here’s a screenshot:
Hey @Bobjt, thanks for bringing this up! I think it really does make sense to make this possible from a workflow perspective. It’s currently not possible, because from a code perspective it may not be so easy. 
Note that you’re always free to file a request on GitHub. Feel free to do this right now!
Currently, the tools are enabled / disabled based on the type of the “current layer”. Maybe I should change that such that for example tile layer tools are enabled as long as at least one tile layer is selected. In addition it may not be so hard to consider a layer selected, as long as either it or one of its parent layers are selected.
Blender differentiates between selected and active objects, the latter being a special selected state which only one object - usually the last selected one - can have. Maybe a similar logic could make sense here?
Well, that is part of the problem here. Tiled has the same logic, where there is one “current” layer and a list of “selected” layers. But too much logic is based solely on the “current” layer (like whether a tool should be enabled).