Alter behavior of the zero button in PiP mode. The exact behavior may be
configured by changing the value of the 'Behaviour of 0 key in PiP-mode'
property in the settings menu. Possible values are:
- standard
the behavior of the zero button is remains as is (switch to last channel)
- swap
the zero button swaps the pip service with the active
- swap and stop
the zero button swaps the pip service with the active and then turns
pip off
- stop
turns pip off
Patch by John Holland <johnbock@i-have-a-dreambox.com>, with some
modifications.