Xchat is a gtk application, of course. There are lots and lots of pages on the web telling developers about gtk's gtk-cursor-blink property (and related properties like gtk-cursor-blink-timeout) and what they do in at a library level, so it's clearly possible. But I found nothing about where a user should set these properties to make gtk find them.
Here's the answer. Add to $HOME/.gtkrc-2.0 (or any other file loaded by $HOME/.gtkrc-2.0):
gtk-cursor-blink = 0
I had to restart X (maybe shutting down all gtk apps would have been enough) before I saw any effect.
While I was searching, I did find a nice page on How to disable blinking cursors in lots of different apps. Its gtk section didn't seem to do anything here (maybe it only works if a gnome desktop is running), but it's a good page nontheless, full of useful advice for turning off cursor blink in other programs.
[ 20:50 Jul 28, 2007 More linux | permalink to this entry | ]