Settings

[Stanley Mortimer]

Ther is a button in roof marked off what is this for 

[chrisramsden]

Yeah,  I have one too, in my Auris. I think it's to do with the intruder alarm, but I haven't found any instructions for use. 

[FROSTYBALLS]

Probably disables the interior sensors of the alarm - useful for owners who sometimes have pets in the car whilst they're away from the car.

[Big_D]

It's for turning it "Off" (sorry, couldn't resist).

Frostyballs is right.

The intrusion sensor detects intruders or movement in the vehicle.
This system is designed to deter and prevent vehicle theft but does
not guarantee absolute security against all intrusions.
■ Setting the intrusion sensor
The intrusion sensor will be set automatically when the alarm is set.
(P. 145)
■ Canceling the intrusion sensor
If you are leaving pets or other moving things inside the vehicle,
make sure to disable the intrusion sensor before setting the alarm,
as it will respond to movement inside the vehicle.
Turn the power switch off.
Press the theft sensor off
switch.
A message will be shown on
the multi-information display.
The intrusion sensor will revert
to on each time the power
switch is turned to ON mode.