To reproduce the issue :
1) Edit the style-jedit-issue.css attached file
2) Try to type something in this file
3) Cursor deasappears cpu usage grows.
4) No error message (in the right bottom corner), error in log file (see txt attachment) before freezing
5) After a while cursor apperas again
@media Error detected by sidekick shouldn't be errors (see screenshot in attachment), I don't know if this is the cause of the issue.
jEdit version : 5.1.0
Sidekick version : 1.6
XML version : 2.8.7