[tde-users] How did Firefox running in Trinity suddenly become full screen?

Hello, I was in the middle of making a donation to a non-profit, in Firefox running in Trinity, when suddenly, for no apparent reason, Firefox became full screen, and there seemed to be no way to get out of it. I presume I must accidentally have typed some key combination that caused it. Does anyone know what key combination that would be? And once it happened, how to get out of it? I had already entered my debit card details, etc, and now, not only had Firefox become full screen, but the top part of the Firefox window, including the address bar, had vanished as well. The ENTIRE screen was now taken up by the main display area of Firefox. The Trinity panel, which I always have at the bottom of the screen, had vanished, and there was no way to get it back. It was very alarming, because all my debit card details were there in the Firefox window, now taking up the entire screen, and I could not even see the Firefox address bar, to check that the green padlock was still there, and there was no green padlock to click on, to check it really was secure, and it really was the correct website. I desperately tried various key combinations including esc and other keys, but nothing worked, until eventually, possibly ctrl + alt + esc, I am not sure, the x mouse pointer appeared, and I must have clicked on the Firefox window with that, although I don't remember doing so, because eventually that full screen Firefox window started to vanish, and the Trinity panel came back into view. I guess the fact that the top part of the Firefox window vanished as well, so the entire screen was taken up by the main display area of Firefox, might indicate that this is a Firefox issue, rather than a Trinity issue, so this might be the wrong forum. Sorry if that's the case. I have been using Trinity continuously since about March 2017, and I think it's really great. Nothing like this has ever happened before. Thanks. With best wishes, Chris Austin