Toggle workce path

[Vebjorn Ljosa]

* Erik Harrison <erikharrison at gmail.com>
| Actually, what I'd like is a key that always returns to the previous
| workspace. I think that generalizes the feature nicely.
| 
| Either a single keyboard shortcut, or alternatively, have Ctrl+Fx
| return you to the previous workspace if already on workspace x. I
| would use something like this.

I like the second idea: have workspace_x_key return you to the
previous workspace if you're already in workspace x.  

Oliver, does this sound acceptable to you?  The few lines it takes to
implement this would be localized to workspaces.c, and would therefore
not bloat the rest of xfwm4.

Vebjorn