I would love to create a custom on-screen display app for my laptop, seeing as the manufacturer-supplied one is utter garbage. I'm out to write an app that will show things such as volume control, screen brightness, wireless antenna status and so forth. I'm not sure what info I'd need to know to begin creating something like this (interfaces for grabbing key/button presses, system priority, any other relevant data) and wondered if anyone could help point me in the right direction. If possible I'd like to develop it in C#.
For example, when I hold in the "Fn" key on my laptop keyboard and press the "F5" key, the volume is decreased. There is a visual representation of this action by way of an on-screen graphic that shows the current sound level being decreased. I want to replace the native graphic because, well, I just don't like it :D.