The big thing that remains to be done, as far as the layer selector goes, is updating the selector appropriately when layers are reordered, removed, or added (e.g. via the XML editor). There are of course also the cosmetic issues we've previously discussed.
For the remainder of issues, the entries in Roadmap should pretty much cover them. Anything with (DONE) on it should work now.
So have you enabled the visibility support? Can you make the visible/locked buttons functional already?
Something we do need to discuss is what "move to {prev,next} layer" should do. Should it move the current selection to the next/previous layer, or simply switch layers without moving the selection anywhere?
I think it should move the selection. It would be counterintuitive to have menu commands for something which can be done simply by clicking on the layer widget. Menu commands are supposed to do some "real" changes. So I think these commands should be called "Raise to next layer"/"Lower to previous layer" in line with other raise/lower commands.
Alternateively, should we have a separate arrangement for shuffling things beteen layers, or what?
In principle it's doable by copy/paste but having a dedicated couple of commands for moving things across layers is convenient.