I have tested it on my 7290 OS 3.8 (Rogers) and it works.
For those that might not be aware, the 7290 has a 2 level backlight (low and high). The application defaults to force the low level backlight on and remained on after several minutes. There are no settings in the program to default to high.
Point of interest: I noticed that the program does not disable button control of the backlight (perhaps this was intentional, but I haven't seen this mentioned anywhere as yet). Depressing the power button raises the backlight to the high level, as usual, and five minutes later, it was still on and in high mode. If you depress the button again, if turns the backlight off, but a moment later, the application turns it back on in the low mode.
Bottom line, this little routine does the trick on the 7290, even with OS 3.8, and doesn't interfere with the high/low choice.