part in the upper pane of the window

Hi, this is a mystery part... I don't know what it's called, so I don't know what to search for. It's on the frame that goes around the glass, on the upper part of the window. I thought it might be a takeout clip, but it's not in the right place to be that, I don't think. It moves in and out like a takeout clip. One of the photos shows a broken one - it is hard to open it because it's broken. These windows don't appear to have take out clips. I'm ordering some new channel balances, so I thought I'd see if you knew what these are, so I can replace these as well. Thanks so much!