The scenario is: you have (on a KDE 4.2 desktop) a panel with fading out enabled. You use Kopete for instant messaging, but don't want sound notifications for incoming messages. Also you don't want popups when the chat window is actually focused.
The solution (at least for me) is: a little python script, some dbus magic and use of kdialog. You set up a notification on incoming messages and type your script in the "run command" text input field. Note that you have to give the path in apostrophe`s, else it will fail. The script does following: