Is there a best way to do that kind of effect ?
And most importantly when the loop ends, the backlight of the phone is turned off.
Is it possible to turn it on ? I tried and use the DeviceControl class without success.
IMHO, it is not the best way to do flashing.
If you want to make your screen darker, you may use 2 approaches:
1) Nokia API's DirectGraphics. Use the transparency. This method is very nice one but only if you orient only on Nokia phones.
2) Use dark textures. This method will work everywhere but requres twice more memory... If your game is not a big one - use this method.
You're right, we could use the Nokia's API. Unfortunately I forgot to mention that our application is not a game and uses Screen objects instead of Canvas.
If only this damned vibrator could be controlled ... :-(