Currently, you cannot select all objects (Ctrl-A) on a page unless you chose to unlock any locked objects. This makes sense. But I would also like to lock all objects on a page, which is not possible by using Ctrl-A and the lock icon.

Since I sometimes get a little mouse crazy and shift my objects inadvertently, is it possible to extend the object locking function by providing a "lock all" option?

Yes it is! try the ALT+L to lock all and the ALT+U to unlock all (or the corresponding 'edit' menu items).

Thank you Harpo. One day I shall buy glasses... if I can get my eye uncrossed.