startcenter: Remove useless menu entries.

Change-Id: Ie886beceb57201ee1a0893943c455d5f87b0d6cc
Force SetBackground() only if the appropriate settings changed.

Otherwise, when you use SetBackground() to set a color, it will be changed to
white the next time the UpdateSettings() is called whatever you do ;-)

Change-Id: I508a049a327fa9be5035bdb19050d6bcb53a2bfe
Use rollover color in the native case.

Otherwise, the text on the button easily becomes invisible.

Change-Id: Ia812706559fbee4ce4ccb1f7610cfd235b1dc5c3
startcenter: Rework completely according to the new design.

Only the background bitmap that will show behind the buttons is missing at the
moment, will come later.

Change-Id: I60e8f74ab28383ce1e891367ba5d2aff23d787ff
startcenter: Thin line around the Help and Extensios buttons.

Change-Id: Id9433a32a9787673fbb266d6465f0bd89f919a40
startcenter: Motif image now works too.

Change-Id: Ieecd2e8ee010b06b64a792e0fcad744c66c5f79e