If there is a ColorMap for this viewport, then the value will be stored in the ColorMap.
The selected color register is changed to match your specs. If the color value is unused then nothing will happen.
NOTES
Lower order bits of the palette specification will be discarded, depending on the color palette resolution of the target graphics device. Use 0xffffffff for the full value, 0x7fffffff for 50%, etc. You can find out the palette range for your screen by querying the graphics data base.