I know it's a bit of a stretch considering it's ultimately opinion (but most UX is) but I'm coming up blank on a visual concept I could use to "iconify" the functionality of "Keep Open" to the user.
Scenario; Large lists with multiple parts of each item that expand and collapse when an item is actively selected or not. However I do provide an option to keep all the nested expandable/collapsible content open even when the item doesn't have active selection.
First I gave them a nifty animated pushpin to give the visual of "pinning" an item in place.
They didn't like it. I tried some other things, they didn't like those either. They opted for me to basically use the In/Out arrow visual that is basically the universal "Make Full Screen" icon like you would see on any youtube video etc.
Except it bugs me lol, and I would personally be confused by this since it doesn't make anything full screen.
So the question is, there a common place icon visual that would convey the concept of "Keep EVERYTHING in this item expanded even when it's not selected?"
If this is too general of a question just seeking inspiration please feel free to say so before going on a down-voting tirade please so I can just del it. ;)