Full screen reset

I’m new to mailspring. I clicked on the button . How do I return to a normal screen?

Hey! Could you please describe anything that could help us point out where or how the issue happens?
Do you have any errors you are facing? If so please send them.

Solved! I needed to reinstall mailspring to figure it out, the toggles full screen. When I was in full screen I couldn’t see anything indicating how to get out!
Thanks
Creighton