how to end full screen mode in screen sharing, how to end full screen mode in screen sharing

I inadvertently hit the 2 little arrows invoking full screen mode while in the screen sharing app. I can't get out of it now, and returned to the windowed mode. Help says to click the 2 little arrows, but I'm not being given 2 little arrows to click.

I see the screen sharing window, no border, against what looks like a background of denim.

pressing esc does nothing.

thanks for clues!

ray