That's due to the process used by applications to launch the prefered browser. They can look at /etc/alternatives/x-www-browser or use "kfmclient openURL" to launch defined prefered browser in kde. There is no solution to this except if all gnome and kde applications use the same process to launch the browser. This is the reason the bug occurs with thunderbird, since this one doesn't use kfmclient.
I'm affraid there is no solution waiting for portland -- In Kubuntu Konqueror windows are opened sometimes as "Konqueror" and sometimes as "X-www-browser" https://launchpad.net/bugs/44791 -- kubuntu-bugs mailing list kubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/kubuntu-bugs
