rc (LONG) - returns
The handling routine must return the nearest available RGB color to that requested (rgbColorOut), or GPI_ALTERROR if an error occurred.
Possible Errors Detected: When an error is detected, the handling routine must call WinSetErrorInfo to post the condition. Error codes for conditions that the handling routine is expected to check include:
PMERR_DEV_FUNC_NOT_INSTALLED
PMERR_INV_COLOR_OPTIONS
PMERR_INV_HDC
PMERR_INV_RGBCOLOR