I have written an article on CodeProject that describes in detail how to set up your first OpenGL GLUT window with multiple sub-windows, and provides you with a template for your OpenGL applications. It can be used in the following ways:
- Understand GLUT sub-windows
- Learn new GLUT event handlers
- Use the code as template if you ever needed a Graphics program with multiple sub-windows
Make sure you read the Visual C++ 2015 section in the article to avoid any issues in running the program.
Check it out, and let me know if you find it useful.