Given your comments to the other questions your problem is simply, that you call glutMouseFunc
without a GLUT window. Trying to register GLUT event callbacks without proper initialization or without a GLUT window created will crash your program.
You also say "GLUT interferes" with your actual window. So why would you try to register a GLUT callback at all if you don't have a window that could actually receive the events for GLUT to dispatch?
You should use the mouse event handling of the window you've already got. And what are you using GLUT for then anyway? The whole purpose of GLUT is to create a window for you and do event management. If you don't use GLUT for that, then don't use GLUT at all.
If it's for the teapot, well, you can have that without GLUT as well.