Hello everyone,
New panel applets were introduced to the newer versions of Ubuntu. They improved the experience, because of their features, but they also created some inconsistencies in the GNOME Panel. If I remember correctly, it used to be that only the Menu Bar had associated elements (Applications, Places, and System buttons). With the new Indicator Applet and Indicator Applet Session, some icons on the right end of the top panel behave differently.
What are your thoughts?
This separation is addressed in the fact that they are getting rid of the notification area, moving all icons to the indicator applet. The clock applet has a new version in the works as well.