LRU sorted document switching
will keep track on view activation
the CTRL-ALT-O list is LRU sorted, latest used doc first
pre-seletected is the previous used doc
just cursor down to broswe in LRU history order
we can't have CTRL-ALT-LEFT/RIGHT do that without such a dialog, otherwise you just would
swap between the latest 2 documents, as as soon as the next one is activated, the last
used one will be next in lru stack