A number of menu items shown under Edit are greyed out when the RT editor is used - caveat, they still work when initiated with a keyboard shortcut (examples cmd-z and cmd-y). When switching to the Markdown editor these commands can again be selected from the menu (not greyed out any more).
(this happens on the mac desktop version)
Just realize that this b(ug)ehaviour is still in place in version 1.8.2., at least under osx.
Yes I think the commands would somehow need to be tweaked so that they work with the Rich Text editor too.