Let me add my vote for this feature. I've always wondered why <CNTRL-,> was popping bookmarks instead of just navigating up the stack.
This would be very useful when I'm, in effect, going up and down the bookmark stack trying to get my head around some code. Currently after hitting <CNTRL-,> and you decide you need to go back to the previously viewed code, you have to repeat all of the navigation commands (e.g. <CNTRL-/> and then scroll through the references and to find/select the desired reference) ... even the "Navigate Forward" button is greyed out after hitting the <CNTRL-,>