c++ cross platform GUI?

Question

Hello, I need for work to create a cross platform project that runs on linux (both pc and raspberry). Usually we program in C# because our previous projects run only on windows. C# and Net framework are extremely powerful and I like them very much but unfortunately i found a little bit tricky to use Mono especially when i try to run complex GUI.
I decided to improve my C++ knowledge because i can compile it almost everywhere with ease, but I still don't know what GUI use especially because i don't know which one is preferable for cross platform projects.
What GUI do you use for your projects on different OS?

Answer 1

QT5