OpenGL examples

[Petr]

@mnrvovrfc the locking of the mouse in the middle of the screen, that was the intended action, simply so that when controlling the movement (rotation in the X/Z axes) it does not happen that you leave the program window with the mouse and the program stops responding to movement. But it shouldn't cause the program to freeze or crash. It worked flawlessly this way in Windows. I will disable this line in the source code for Linux and the problem will be over. Thanks for trying it out.