Created attachment 75853 [details]
System tray screenshot
All apps in ubuntu must support libindicator (aka ayatana) system tray icons, because unity doesn't show legacy system tray icons. Fortunately KDE support both ayatana and legacy system tray icons. In KDE 4.10 systemtray plasmoid was rewritten which caused a regression. There's a problem which appears when sni-qt package is installed. Some qt apps are using sni-qt to provide ayatana consistent system tray entries. Those apps' system tray icons are just displaying generic "missing icon" instead of normal system tray icons (see screenshot). Temporary workaround is to uninstall sni-qt package.
*** This bug has been marked as a duplicate of bug 311555 ***