about GdkColor

[Jun Ma <ma_jun1973 yahoo com>]

Hello,

As we know a color can be described by RGB. RGB is
enough. But, why does GdkColor use the following
structure: 
  struct GdkColor {

  guint32 pixel;
  guint16 red;
  guint16 green;
  guint16 blue;
};

What is the 'pixel' in GdkColor? What is the relation
between 'pixel' and RGB? How to know the pixel's value
from RGB?

For example, when the color is red or RGB(65535, 0,
0), what will be the 'pixel'?

Thanks.

Jun

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