SlickEdit Pro 2023 (v28.0.0.3 64-bit Qt5) on Ubuntu 22.04.2 LTS with multiple monitors.
Whilst I was editing away, suddenly keyboard input did nothing in Slickedit. I could click on File->Save to save my work. I opened Key Bindings and tried to enter something there, no go, nor in the Options search.
When this started, I saw "Background tagging is searching for files to tag in tag file '<one of my apps>.vtg'.
I could click to other windows and the keyboard worked fine.
I File->Exit-ed Slickedit and restarted it and the keyboard started to work again.