I'm trying to create a simple GUI program that stays on top and shows an image plus few buttons with variable opacity for the whole window to use like onion skin over other programs. after installing Code::Blocks I'm facing lots of choices for the project type and I have no idea which one I should choice to be able to build for both windows and macOS platforms.
I'm trying to make it a single file program or contain everything in the same folder, without the need for anything to be installed, that's why I've chosen C++ after reading about other possible solutions, I'll appreciate any information about that topic as well.
On Windows you would normally use the Win32 GUI project option, which will use the WinAPI and thus only be compatible with Windows. If you want to support both Windows and MacOSX with the same code base you need to use a platform independent GUI framework such as QT or GTK+.