Your code will work if you change your method to this...
private Brush DrawingColorToBrush(System.Drawing.Color color)
{
Brush ret = null;
BrushConverter m = new BrushConverter();
string s = "#" + color.ToArgb().ToString("X8");
if (m.CanConvertFrom(typeof (string)))
{
ret = (Brush) m.ConvertFromString(s);
}
return ret;
}
The key is to prepend the string with the '#' character.