> Obviously the bottom right corner of a rectangle cannot be 10,10 if the top left corner is 0,0 What you said is only true for a mathematician. In mathematica

> Obviously the bottom right corner of a rectangle cannot be 10,10 if the top left corner is 0,0 What you said is only true for a mathematician. In mathematical conventions, Y axis is directed upwards. For programmers however, Y axis is usually directed downwards. In programming, the top left corner of a window has coordinates [ 0, 0 ], and a rectangle with top left [ 0, 0 ] and bottom right [ 10, 10 ] is a perfectly valid one.