How can i write a program that writes to the desktop? Below all windows, but ontop of the wallpaper? I know this is possible because i have seen things like root-tail (http://oldhome.schmorp.de/marc/root-tail.html) But that program is in C. Can someone help me reproduce this kind of thing in c++?
The majority of C programs can be made to build in C++ with minimal or zero changes. Which doesn't make such a program a C++ program----that's more about style and design----but it does beg the question of why you feel a need to do such a conversion if the code works well as-is.
If it can be done in C it can be done in C++. The only thing moving to C++ gives you is the ability to streamline the code in certain ways. It's natural---even expected---that at a few places, you'll have to interface with C APIs to get things done in C++.