I have been playing around with pwa-like experiences, and as part of that I tested "kiosk mode".
For those who don't know, you can start a "kiosk window" with the command firefox -kiosk --new-window <url>, which will open that url in fullscreen without a titlebar, right click menu, any overlays like the link preview or loading text, ...
I cancelled the fullscreen flag of my window, and had a resizable fully functional website in a frameless window.
Which was great and all, until I realized that in my running profile now every newly opened window is also in kiosk mode, and right click was globally disabled. My running firefox instance has been infected by the kiosk disease.
Anyway, it's not a large issue, I can just restart my infected instance. But I hate restarting my browser, it usually runs for multiple months.
My question is, is it possible to leave kiosk mode without restarting firefox?
Are you trying to use kiosk mode in a way that was never intended? Kiosks being public use terminals like in retail or used for search only terminals at public places?
This sounds like an XY problem to me intuitively since your use case wouldn't naturally match a kiosk situation.
Yes, this is more of a recovery operation. Whatever the fix may be, modifying the browser itself to open a window without decorations would be easier.
There are some usecases in which you really don't want to restart your browser.
The easiest way to update your kernel is to restart your pc, yet there is a market for live-patch kernels.
If someone accidentally infects their instance with kiosk, it may occasionally be preferable for them to follow a complex procedure to recover the instance, rather than doing the "simple" thing of restarting it.
Restarting may solve many problems, but there is a more difficult but less invasive solution almost every time.
Much like reinstalling may solve even more problems, but you can see that doing a reinstallation is not usually the right course of action.