Functionality to mark a slide complete

I do not believe this functionality alread exists but I'm quite sure I'm not the only one that would love to have it added. 

Now when working in a larger powerpoint slide deck I start with adding a "traffic light" to my slides that's red, and when the slide is finished I turn it green. Then, before presenting I have to delete all traffic lights before the deck is truly ready. This way I can keep track of which slides still need attention and prevent myself from spending time on slides I shouldn't.

Now I believe it would be very nice if it was a built in feature where you can mark individual slides as "complete / final" or "needs attention" with visual feedback of this status in for example the navigation pane. 

How do others handle this and is there a trick I do not know of?