Back Arrow Broken In Xcode?

Is there keyboard command to go back/forward one file at a time.

Xcode 3.2 changed the behavior of Cmd-Opt <-- and -->. As noted in another question, they do not operate on a file level like in previous versions of Xcode, but on an "edit point", making it cumbersome to flip through a list of files (the quick way to do it, since Xcode does not support Tabs, as in Eclipse).

Rob Keniger found a partial solution that he noted in another post:

"Hold down the option key while you click the forward/backward arrows ..."

But this requires fiddling with the mouse. Is there any way to do it with the keyboard only?

EDIT: Later versions of Xcode (v7.2+) now have a Navigate menu (and it changes the keyboard shortcuts yet again):