rc (LONG) - returns
On completion, the handling routine must return the nearest available RGB color to that requested (rgbColor), 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_DATA
PMERR_INV_COLOR_INDEX
PMERR_INV_COLOR_OPTIONS
PMERR_INV_HDC