The width in pixels of the screen.
The height in pixels of the screen.
The screen number.
The number of color planes in the screen.
A list of all of the interfaces visible on the screen.
When the CAPI initializes itself it creates one screen object per monitor screen, and they are then used to specify where a window is to appear. They can also be queried for information that the program may need to know about the screen that it is working on, such as its width, height and depth.
(setq screen (capi:convert-to-screen))