Explaining Coordinates in Trillian

From TrillWiki

When I first started learning to skin Trillian, I was always cutting the right edge or bottom edge off my buttons. The reason for this was the way Trillian handles coordinates. It's easier to explain this visually:

Pictured above is how I thought the coordinates would work. As you can see the top left pixel of the blue area would be 0,0, the bottom right corner would be 2,2. This is unfortunately not how Trillian handles the coordinate system.

Instead, this is how it handles them. Note the different location of the numbers along the edges. Imagine there is a big invisible grid laid over the top of your image and we don't count the pixels, we count the actual grid lines instead.

If you drew a bounding box around the blue area in this diagram, the top left coordinate of the box would be 0,0, and the bottom right is 3,3.

Because of this, you can see how I was accidentally cutting the edges of things!