glutReshapeWindow requests a change in the size of the current window. The width and height parameters are size extents in pixels. The width and height must be positive values.
The requests by glutReshapeWindow are not processed immediately. The request is executed after returning to the main event loop. This allows multiple glutReshapeWindow, glutPositionWindow, and glutFullScreen requests to the same window to be coalesced.
In the case of top-level windows, a glutReshapeWindow call is considered only a request for sizing the window. The window system is free to apply its own policies to top-level window sizing. The intent is that top-level windows should be reshaped according glutReshapeWindow's parameters. Whether a reshape actually takes effect and, if so, the reshaped dimensions are reported to the program by a reshape callback.
glutReshapeWindow disables the full screen status of a window if previously enabled.