Each created window has a unique associated OpenGL context. State changes to a window's associated OpenGL context can be done immediately after the window is created.

The display state of a window is initially for the window to be shown. But the window's display state is not actually acted upon until mainLoop is entered. This means until mainLoop is called, rendering to a created window is ineffective because the window can not yet be displayed.

The value returned by createWindow and createSubWindow is a unique identifier for the window, which can be used with currentWindow.

Mark the normal plane of given window (or the current window, if none is supplied) as needing to be redisplayed. The next iteration through mainLoop, the window's display callback will be called to redisplay the window's normal plane. Multiple calls to postRedisplay before the next display callback opportunity generates only a single redisplay callback. postRedisplay may be called within a window's display or overlay display callback to re-mark that window for redisplay.

Logically, normal plane damage notification for a window is treated as a postRedisplay on the damaged window. Unlike damage reported by the window system, postRedisplay will not set to true the normal plane's damaged status (see damaged).

Also, see postOverlayRedisplay.

Perform a buffer swap on the layer in use for the current window. Specifically, swapBuffers promotes the contents of the back buffer of the layer in use of the current window to become the contents of the front buffer. The contents of the back buffer then become undefined. The update typically takes place during the vertical retrace of the monitor, rather than immediately after swapBuffers is called.

An implicit flush is done by swapBuffers before it returns. Subsequent OpenGL commands can be issued immediately after calling swapBuffers, but are not executed until the buffer exchange is completed.

If the layer in use is not double buffered, swapBuffers has no effect.

Note that the requests by windowPosition, windowSize, and fullScreen are not processed immediately. A request is executed after returning to the main event loop. This allows multiple requests to the same window to be coalesced.

windowPosition and windowSize requests on a window will disable the full screen status of the window.

Controls the position of the current window. For top-level windows, parameters of Position are pixel offsets from the screen origin. For subwindows, the parameters are pixel offsets from the window's parent window origin.

In the case of top-level windows, setting windowPosition is considered only a request for positioning the window. The window system is free to apply its own policies to top-level window placement. The intent is that top-level windows should be repositioned according to the value of windowPosition.

Controls the size of the current window. The parameters of Size are size extents in pixels. The width and height must be positive values.

In the case of top-level windows, setting windowSize 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 to the value of windowSize. Whether a reshape actually takes effect and, if so, the reshaped dimensions are reported to the program by a reshape callback.

Request that the current window be made full screen. The exact semantics of what full screen means may vary by window system. The intent is to make the window as large as possible and disable any window decorations or borders added the window system. The window width and height are not guaranteed to be the same as the screen width and height, but that is the intent of making a window full screen.

fullScreen is defined to work only on top-level windows.

X Implementation Notes: In the X implementation of GLUT, full screen is implemented by sizing and positioning the window to cover the entire screen and posting the _MOTIF_WM_HINTS property on the window requesting absolutely no decorations. Non-Motif window managers may not respond to _MOTIF_WM_HINTS.

Controls the display status of the current window.

Note that the effect of showing, hiding, and iconifying windows does not take place immediately. Instead the requests are saved for execution upon return to the GLUT event loop. Subsequent show, hide, or iconification requests on a window replace the previously saved request for that window. The effect of hiding, showing, or iconifying top-level windows is subject to the window system's policy for displaying windows. Subwindows can't be iconified.

Change the cursor image of the current window. Each call requests the window system change the cursor appropriately. The cursor image when a window is created is Inherit. The exact cursor images used are implementation dependent. The intent is for the image to convey the meaning of the cursor name. For a top-level window, Inherit uses the default window system cursor.

X Implementation Notes: GLUT for X uses SGI's _SGI_CROSSHAIR_CURSOR convention to access a full-screen cross-hair cursor if possible.

Setting pointerPosition warps the window system's pointer to a new location relative to the origin of the current window by the specified pixel offset, which may be negative. The warp is done immediately.

If the pointer would be warped outside the screen's frame buffer region, the location will be clamped to the nearest screen edge. The window system is allowed to further constrain the pointer's location in window system dependent ways.

Good advice from Xlib's XWarpPointer man page: "There is seldom any reason for calling this function. The pointer should normally be left to the user."