Forgot something...

The copy transformation modifier key is now Option instead of Command. Instead of drag a copy being Cmd+D+Cmd, it's Cmd+D+Opt. Same for mirror and rotate.

Window | Floating Palettes | Show Quick Layers (Ctrl+L).

Quick Layers Palette

The Quick Layers palette enables you to:

Unhelpfully:

• Toggle the display of all the layers. All the showing layers become hidden, all the hidden layers show. Shrug.

• Ditto for lock/unlock. Shrug.

Very helpfully, under 'Selection's Layer':

• Hide, lock, or unlock the layer of selected elements, even for multiple layers at a time. Similar to the 'Layer' sub-context menu.

Remember?

Unhelpfully again:

• Hide or lock all layers. Big shrug.

The palette will close when you quit ArchiCAD, unlike the standard palettes. Just reactivate it when you start with Ctrl+L.