Comment 7 for bug 80444

OK, I got a suggestion on a forum -- http://ubuntuforums.org/showthread.php?t=336229 -- and with a bit of twiddling I got kcontrol to show the menus.

I don't know what caused it. I suspect a malformed package or some conflict, I don't know. This machine was updated using apt-get from dapper through edgy to feisty, so I wouldn't be surprised if the package manager somehow got confused. (It happened before.)

According to the suggestion, I was supposed to have a file /etc/xdg/menus/kde-applications-merged/kde-essential.menu on my system. After a bit of searching, I realized on my system there was /etc/xdg/menus/kde-applications-merged/kde-essential.menu/kde-essential.menu (the file was in a same-named directory). I renamed the directory and moved the file in its stead, and now kcontrol works.

By works I mean it shows the various applets and they seem to do stuff. I've still got the problem with the fonts, but I'll file a different bug for that.

If anyone wants to try and diagnose the issue with kcontrol -- it seems it happened to others, too -- let me know. I can post an archive with the /etc/xdg/menus/ directory and whatever other info you might need.

By the way, I noticed there's also a file called "kde-essential.menu.dpkg-new" that's identical to the file I needed. I suppose the package manager tried to create it and couldn't because of the directory of the same name.

I don't know enough of apt's internals to trace the issue to the source, but I'm quite sure now it's an update issue. If you need anything, don't hesitate to ask.