Comment 2 for bug 991318

Thank you! It looks like something went wrong when resizing the window. The move button obviously shouldn't become unreachable. Do you remember what you did right before the window got into that state?

Please post the output of
$ xrandr
$ gsettings list-recursively apps.onboard.window

After you have done this, please try resizing the window again. The move button is supposed to snap into view after each resize action (also when hiding and on exit).
Let me know if that happens.