Page should block certain interactions from tabbing out

I was just banned from the C Language Test for tabbing out 3 times.
My Problem was that I’m used to press ctrl+s to save my code (which usually also autoformats it in my IDE), but in the browser this assumes I want to save the loaded page and opens up a window to pick the location to save it to.
Every time I instantly went back to the fullscreen mode after the warning, but saving my code before running it is just a reflex.
Surely as a page which aspires to teach programming catching a ctrl+s with 3 lines of java code isnt asking too much lol… I know of course its my fault for trying to save code in an online editor in the first place, but I think its pretty obvious that someone hitting ctrl+s who then restores fullscreen within 3 seconds isnt atually trying to tab out and cheat… If I wanted to actually cheat I would just do it on my tablet or smartphone…