Comment 7 for bug 956863

Johannes's description is accurate for the bug in my experience.

In addition I have notice that the problem with the shadow being drawn can occur on the presenter console as well.

This also links to a wishlist item bug #853865 where I describe this aspect as follows;
"If I click within the external display, that shadow disappears from the audience view, and appears on the presenter view. When I click on the presenter view on the laptop screen, the shadow returns to the audience view..."

This behaviour does allow one to remove the visible shadow from the audience view, albeit temporarily.

The wish list bug also asks for the top panel to be optional on the audience (external) display, as the launcher now is.