_x expects the maximum width of a graphics window. The width is
measured in pixels.
_y expects the maximum height of a graphics window. The height is
measured in pixels.
DDDDEEEESSSSCCCCRRRRIIIIPPPPTTTTIIIIOOOONNNN
mmmmaaaaxxxxssssiiiizzzz specifies the maximum size (in pixels) of a graphics window. Call
it at the beginning of a graphics program before wwwwiiiinnnnooooppppeeee. mmmmaaaaxxxxssssiiiizzzz takes
effect when wwwwiiiinnnnooooppppeeee is called.
You can also call mmmmaaaaxxxxssssiiiizzzz in conjunction with wwwwiiiinnnnccccoooonnnn to modify the
enforced maximum size after the window has been created. The default
maximum size is ggggeeeettttggggddddeeee((((GGGGDDDDXXXXPPPPMMMMAAAA)))) pixels wide and ggggeeeettttggggddddeeee((((GGGGDDDDYYYYPPPPMMMMAAAA)))) pixels
high. The user can reshape the graphics window, but the window manager
does not allow it to become larger than the specified maximum size.