How to keep the Backlight on
Backlight on/off works on user interaction with the device, if there is no activity for a specific time period, the backlight goes off.
One way to keep the Backlight on is to use the ResetInactivityTime, which resets the inactivity time counter.
Note that backlight is a major energy consumer and preventing backlight to go off should not be used without true need and proper consideration. More information on energy efficiency can be found from a dedicated power management section in Nokia Developer.
// you can implement this code in the timer so that it continuously resets
// the inactivity time