Kill app long press timeout: fix indiscriminately killing in clean instalations (2/2)

- Put a method to update state
- include default value in xml file
- fix the code

Change-Id: Id19be32e208084e1e841fc98105ea8b1cac420a9
make LinearColorBar themeable
Move colors to resources and use them instead.

Change-Id: I923e5daa219f302dc24e62faab666483109e6620
Signed-off-by: Dirk Rettschlag <dirk.rettschlag@gmail.com>