Widgets embedded in the systray (Through the Extra Items) dialogue are expanded to their widgets when they are hidden in the drawer, rather than being iconified as they are when they are in the panel. See attached URL for example. 

Reproducible: Always

Steps to Reproduce:
1. Create a systray plasma applet
2. Through the System Tray Widget Settings dialog add a Device Notifier in the Extra Items area
3. In the same window, switch to Entries and set Device Notifier to Hidden
Actual Results:  
Pull open the drawer and you will see the contents of the device notifier widget hidden behind the other items. 

Expected Results:  
Widgets should stay iconified until clicked

This is not restricted to icons that are explicitly hidden; Auto icons which are inactive (and thus put in the drawer) also face this problem. (see Software Updater and Manage Print Jobs in URL). This happens to any widget which is hidden in the drawer.