Comment 17 for bug 997004

Same problem here. I wonder who decided this was a nice "feature" to include. Apparently the files that have been opened as read only due to the line length restriction are logged somewhere in ~/.kde/ and are opened as read only in all future instances without a warning.

A quick and dirty fix:
1) open a terminal
2) remove the .kde directory from your home directory
     user@machine:~$ rm -rf ~/.kde
3) open kile
     user@machine:~$ kile &
4) allow long lines
     settings --> configure kile --> open/save --> line length limit = 0
5) enable dynamic word wrap (if you want)
     settings --> configure kile --> appearance --> dynamic word wrap
6) close kile and repeat steps 3-6 for kate if you want