I am new in openGL. What I wanted is to cover the screen with a rectangle. means want to give a border to the screen. for that I want to know the size of the screen.
Since at the time of window creation we passed 640X480, so I thought at ( 0,0,0 ) screen size should be 640X480 pixels. but its not true.
Please some body tell me how to find out the size of the screen so that I can draw a rectangle to border the screen.