A typical modern terminal emulator running under X will export WINDOWID that is the X id of the terminal emulator window. With this you could detect key-up ev

A typical modern terminal emulator running under X will export WINDOWID that is the X id of the terminal emulator window. With this you could detect key-up events. I've never seen anybody do this though. The only uses of this I've ever seen are detecting when the terminal emulator goes out of focus and drawing images on top of the terminal emulator. I've not done a detailed survey, but I believe this used to be the most common way of displaying images "in" terminal emulators before terminal emulators started supporting inline images encoded as escape sequences (e.g. iterm2) The problem with having the terminal emulator implement it is getting the terminal emulator to know when to insert these new key-up escape codes into the psuedo-terminal. The terminal emulator shouldn't send them to the psuedo-terminal when it's in raw mode, because every existing program that runs in raw mode won't know what to do with them. And inserting them into a cooked mode pty simply makes no sense. So it becomes clear that the terminal needs a "rawer than raw" (still bleeding?) mode, and some way for the program requesting bleeding mode to communicate that desire to the terminal emulator. Right now, that's not how the whole stack works. A program tells the psuedo-terminal (kernel) whether it wants raw or cooked mode, that's not something that terminal emulator is involved in. You could potentially have a terminal emulator that accepts a proprietary "toggle bleeding mode" escape sequence, at which point the terminal emulator starts inserting key up escape codes into the pseudo-terminal which it assumes has been placed into raw mode appropriately. There's not really any technical reason this couldn't be done, but there's a strong "nobody needs this" social reason for why it hasn't been done. Sure, if you want responsive controls while play aalib quake in your terminal emulator across ssh, you'd want this. But who does that as anything other than a gimmick?