Version:           1.4.5 (using KDE 3.5.10)
OS:                Linux
Installed from:    SuSE RPMs

There is something wrong with the skim interaction concerning gtk2 applications. I usually experience it when I open a website with HTTP authentication in Firefox. As espected, FF pops up the username/password prompt.
When the skim applet is running, in 50% of the times I can't type anything into the username and /or password fields. Since the text cursor doesn't appear when clicking on the fields, I'd say it seems that skim (or scim?) is blocking the focus to the modal prompt.
Choosing "Cancel" and try again doesn't work.
Choosing "Cancel" and then stopping skim (click on the applet and choose Quit) does help in 50%: the FF authentication dialog would appear, I can type in username and password, all is well. In the other 50%, FF is completly stalled (no reaction on mouse clicks/movement or text input/keyboard shortcuts).

The reasons why I suspect skim to be buggy:
1) The problems described above don't happen when skim is not running.
2) The problems described above don't happen when using scim with gnome desktop environment.
3) The problems described above do happen on every KDE installation I use, independent of HW.
4) A colleague who also uses skim from time to time confirmed the problems above, even with other gtk2 applications.

The behavior above isn't new to KDE, I have experienced it since I started using skim (which was in 2005).