I think that the title is clear !
What I have now is :
System.Drawing.Color uiui = System.Drawing.ColorTranslator.FromHtml(myString);
var intColor = (uint)((uiui.A << 24) | (uiui.R << 16) | (uiui.G << 8) | (uiui.B << 0));
var bytes = BitConverter.GetBytes(uint.Parse(value));
var brush = new SolidColorBrush();
brush.Color = Color.FromArgb(bytes[3], bytes[2], bytes[1], bytes[0]);
1- myString is like #FFFFFF like I said in the title
2- This fails on the BitConverter.GetBytes line which surprises me cause I got the int representation on my Color !
3- Anyway, I know that COlor conversion are not that intuitive but I feel like I'm not doing it right... Is that the good way ?