为什么在win7下,Image1不能透明?

procedure TForm1.FormCreate(Sender: TObject);
begin
Self.Color:=clBlue;
Image1.Transparent:=true;
Image1.Canvas.Pen.Width :=6;
Image1.Canvas.MoveTo(20,0);
Image1.Canvas.LineTo(20, 80);
end;

Image1一直显示白白的背景

是用xp+delphi7做的 在xp下正常

弄个png控件吧，然后就用png图片，一切都解决了。

procedure TForm1.FormCreate(Sender: TObject);
var
  ABitmap:TBitmap;
begin
  Self.Color:=clBlue;
  Image1.Transparent:=true;
  ABitmap:=TBitmap.Create;
  ABitmap.SetSize(Image1.Width,Image1.Height);
  ABitmap.TransparentColor:=clWhite;
  ABitmap.Transparent:=True;
  ABitmap.Canvas.Brush.Style:=bsSolid;
  ABitmap.Canvas.Brush.Color:=clWhite;
  ABitmap.Canvas.FillRect(Rect(0,0,Image1.Width,Image1.Height));
  ABitmap.Canvas.Pen.Color:=clBlack;
  ABitmap.Canvas.Pen.Width :=6;
  ABitmap.Canvas.MoveTo(20,0);
  ABitmap.Canvas.LineTo(20, 80);
  Image1.Picture.Assign(ABitmap);
  ABitmap.Free;
end;