Show panel shadow on full-screen mode

On full-screen mode the panel appears on hover over the image.
This patchset applies the same shadow as when the panel is open to the full-screen panel.
This is done to communicate that the panel is ovelapping the image.

Change-Id: Ia76f2ace6a424bbd26d4d3d43ed213b98ec91006
Merge "Show panel shadow on full-screen mode"