Just a quick tips for those of you needing to blend two colors. Usage is very easy.

// Usage  NewColor:= Blend(Color1, Color2, blending level 0 to 100);
function Blend(Color1, Color2: TColor; A: Byte): TColor;
var
  c1, c2: LongInt;
  r, g, b, v1, v2: byte;
begin
  A:= Round(2.55 * A);
  c1 := ColorToRGB(Color1);
  c2 := ColorToRGB(Color2);
  v1:= Byte(c1);
  v2:= Byte(c2);
  r:= A * (v1 - v2) shr 8 + v2;
  v1:= Byte(c1 shr 8);
  v2:= Byte(c2 shr 8);
  g:= A * (v1 - v2) shr 8 + v2;
  v1:= Byte(c1 shr 16);
  v2:= Byte(c2 shr 16);
  b:= A * (v1 - v2) shr 8 + v2;
  Result := (b shl 16) + (g shl 8) + r;
end;