GLUT - Moving Camera with Mouse (No Click & Hold)

[lmsmi1]

I've tried Lighthouse3D's tutorial, and it compiles fine. However I would like to Keep the mouse in the current "game" window, that way the user can keep looking around without having to put the mouse back in the screen. I think this can be done if I keep the mouse pointer in the middle of the window, but when the user moves the mouse, calculate the movement, and move to that position in the screen.

And also, for the looking with the mouse part: do I use glutPassiveMotionFunc() to use the mouse to look up & down + left & right, in constant frames? I would like to be able to let the user look around freely with the mouse without having to click & hold while dragging. Suggestions?