Mouse and keyboard not getting captured by Xephyr

So, I started a Xephyr window: Xephyr -br -ac -noreset -screen 1280x720 :1 and then started xfce4 inside of that Xephyr X server: Export DISPLAY=:1 startxfce4 This all works fine, but now I want to get my cursor and mouse inside of that Xephyr X server... According to the arch wiki , you are apparently supposed to be able to capture user input by pressing Ctrl+Shift when the window is in focus. But, on my machine, this doesn't actually seem to do anything. So I was wondering if I am doing something wrong here? Also, I can't find anything about this keyboard combo in the manpage, does Xephyr have any documentation that covers stuff like hotkeys?