Fix overdraw and do some layout optimizations

- use a specific layout for the Dashboard and for the Preferences
- use a specific background for the Dashboard and for the Preferences

The main idea here is that you cannot have the same layout / background
because the Dashboard is using the "Z elevation" for having its card
"poping up"

Change-Id: I42b7c91efea14315b8a60cf3876938a7f1d1e0b3