If I understand correctly this feature is now supposed to be available. However, there’s a problem. In the documentation it says
Note: If there is a locked object selected it will be used as a “key object” and all others will be aligned to left part of the locked object. If there are several locked objects selected, the alignment will use the left side of the left-most locked object.
Yet, else where in the documentation it says:
Locked objects and layer folders cannot be selected, moved, or changed. Click the lock icon again to unlock.
This indeed seems to be the case, I cannot figure out how to make a group that includes a locked object. If I select three objects, and then lock one of them (in the panel to the left, for instance), the locked object is no longer selected.
I have no idea how to make use of this feature, and the documentation does not make it clear how I would do so.