DMXAddScreen() will return
True if the screen was successfully attached, and
False otherwise.
False will be returned if the
-addremovescreens command line option was not specified on the
Xdmx(1) command line, the input value of
screen is out of range,
screen is not currently detached,
displayName cannot be opened, has unexpected visuals, or has characteristics that do not match the previously detached screen.
DMXAddScreen() can generate BadLength, BadAlloc, and BadValue errors.