it's not all so simple as that.
All Nokia devices are double buffered.
Some devies are not.
Fine, so you just double buffer all devices, and everythings good then? - NO
, because this is where the fun begins
SOME devices are faulty in the most bizarre way.
Take some (all?) of the Series 60 devices from Nokia (6600, 3650...) do not support colors (defaults to black) on strings written to a buffered image.
So you basically have to write a game that works in buffered and unbuffered mode.
There are countless other bugs, which is why pro games on a phone can be rather tricky (unless you only support 1 phone).