Control keyboard app
Is it possible to write a program using QT which could control the light of the keyboard(connected via USB), control the light I mean change it(keyboard has build-in light? Maybe you could recommend what library i can use for this if there is one?
There are no built-in classes for this in Qt, you will have to use external libraries or OS-specific code.
I think you should check out KDE addon libraries: they definitely do have code for controlling keyboard backlight, as it is being used in all KDE Linuxes.
To add to @sierdzio, what kind of light are you talking about ? What type of keyboard ?