Sorry if this is dim but I can't see what it does, it has a "close" x button and "stick" button.
I believe this is from the plugin DisplayLayerProgress and attempts to show you what it's sending to the LCD on your printer. You can turn this off in the options for that plugin.
Ah that makes sense. Untill I get my printer and run Octoprint on a Pi (not on a PC) a lot of things I don't understand will become obvious. Thanks