CompactApplet: Only draw separator line for panel applets
The purpose of this line is to separate a panel applet's popup from the panel, but when there is no panel, the line gets drawn anyway, has undefined geometry, ends up too big, and looks weird. This commit hides it for the popups of non-panel applets.
To test, Add Kickoff to your desktop and click on it and see that its popup looks normal.
BUG: 439374 FIXED-IN: 5.23