Why is there a leading “#FF” in hexadecimal color values?

Question

I\'m using Expression Blend 3 and am writing some of the XAML by hand, specifically the color values of controls.

I have a list of RGB colors already converted to hex

Answer 1

That may be the alpha component of the color, which represents the opacity (00 -> transparent, FF -> opaque).

MSDN seems to agree with this: Color

16-bit hexadecimal, alpha -- #AARRGGBB