There is currently a serious incompatibility between LyX and IBus (the default input method in Ubuntu and Fedora) that causes various problems:
* The keyboard starts outputting the wrong keys * LyX completely and definitely stops responding * When using arrow keys or page up/down, the movement continues for a long while after the key has been released. If you have experienced these bugs and use Linux, then you may be a victim of this incompatibility. The main trigger is a heavy system load so it happen more often to users with long documents with which LyX is slow. I have just found the reason to these bugs so I wanted to share the workarounds: * Disable IBus just for LyX (if you don't need a special input method): Run LyX with the command line: XMODIFIERS= lyx or equivalently (in Ubuntu) adapt /usr/share/applications/lyx.desktop as follows: Exec=env XMODIFIERS= lyx %F or: * Set IBus to synchronous system-wide (keeps IBus in LyX, but does not solve the third issue and causes problems with the hangul input method): Add the following line to .xsessionrc (create if needed): export IBUS_ENABLE_SYNC_MODE=1 Follow the bug at <http://www.lyx.org/trac/ticket/9362>.