> Nor should it. That kind of sandboxing should be done as a wrapper around a particular program, not in the display server. A nested X server that sanitizes th

> Nor should it. That kind of sandboxing should be done as a wrapper around a particular program, not in the display server. A nested X server that sanitizes the protocol wouldn't be particularly difficult. Also, if your aren't fully sandboxing your potentially hostile application, a keylogger is the least of your problems. The display server isn't going to protect you from actual local attacks and privilege escalations; instead, it will only provide a false sense of security. Nested X servers are a pain, if you've used one - the things you're used to, like functional copy/paste, performant operation, tend to disappear and make this a non-workable solution. Furthermore, if you look at the release not of (e.g.) firejail, a wrapper around a local program, you'll notice that indeed a lot of the revisions are trying to avoid X bugs that let applications act as key-loggers etc. People have tried, and it turns out to be difficult.