AW: AW: AW: AW: AW: making fallback access keys configurable

[Tobias Anton]

> which would break CTRL+Key_O == open.
Indeed, this kind of argument will hold for whatever modifier we assign to
the fallback accesskeys.

But it can only be avoided by assigning a higher priority to the menubar's
actions and further by avoiding to use existing shortcuts as fallback
accesskeys. Is this possible at all, i.e. can we determine whether a given
shortcut is available?

> and having "other UI events" change the state of an
> explicitly requested mode on a user is generally very
> frustrating for users due to "loss of control".

Right. Only when pressing ctrl and releasing it _immediately_ afterwards,
the mode should be entered. The idea of using the absence of other UI events
to detect immediacy still seems valid to me. Any check less strict would
potentially lead to annoyances again.