Yellow flag button at top right of Windows app shows no tool-tip pop-up

[Dave Coder]

I can't tell what this will do when I click it... it shows no explanation when I hover over it:

 

I'm afraid to click it.

Please developers, please just implement tool-tips like tools normally have. I'm dealing with someone else's repo and I don't want to change things without knowing what I'm doing.

I could find no information on what this does using a web search.