I got a weird issue with OpenLP 2.3.6 on Linux Mint 19 Mate 64-bit (based on Ubuntu 18.04 LTS).
I was learning OpenLP on my desktop PC with 1 monitor, while opening web browser. No projector was connected.
When I clicked on Blank Screen icon below the Live box, I was unable to find a way to return to the UI (Menus, Media Manager, Preview, Live boxes, Service Manager, etc). I was just able to right-click on the screen and it displayed a context menu saying: "Reload". Pressing Alt-Spacebar displayed a context menu listing: Minimize, Unmaximize, Move, Resize, Always on Top, Close, but when I chose "Close", it didn't close the fullscreen display either.
I also found that clicking the "Replace live background" icon in the Images and Media tabs would cause the same issue, i.e. fullscreen slide display, without ability to return to the UI.
Is it a bug, or is there actually a way to return to the UI?
Thanks in advance.