Fehlermeldung "zugewiesener Wert wird niemals benutzt"?

[Edgware]

Delphi-Quellcode:

implementation
var    Farbe: tColor;
       Hg   : tBrushStyle;
       Art  : tPenMode;

{$R *.dfm}

procedure TForm1.B_ZeichnenClick(Sender: TObject);
var x1, y1 , x2 , y2 :integer;
begin

with form1.image1.canvas do

begin
 x1:=Random(Width);
 x2:=Random(Width);
 y1:=Random(Height);
 y2:=Random(Height);
 Canvas.Pen.Color :=Farbe;
 Canvas.Brush.Color:=Farbe;
 Canvas.Pen.Mode :=Art;
 Canvas.Rectangle(x1,y1,x2,y2)

end;

end;

procedure TForm1.B_EndeClick(Sender: TObject);
begin
close;
end;

procedure TForm1.R_weissClick(Sender: TObject);
begin
  Farbe:=clWhite;
end;

procedure TForm1.R_pinkClick(Sender: TObject);
begin
Farbe:=clfuchsia;
end;

procedure TForm1.R_schwarzClick(Sender: TObject);
begin
Farbe:=clBlack ;
end;

procedure TForm1.R_gruenClick(Sender: TObject);
begin
Farbe:=clGreen;
end;

procedure TForm1.R_PurpleClick(Sender: TObject);
begin
 Farbe:=clpurple;
end;

procedure TForm1.B_LeerClick(Sender: TObject);
begin
if B_Leer.Caption='leer' then
begin
 Hg:=bsSolid;
 B_Leer.caption:='gefüllt';
 end
else begin
 Hg:=bsClear;
 B_Leer.caption:='leer';
 end
end;

procedure TForm1.B_NormalClick(Sender: TObject);
begin
if B_Normal.Caption='normal'then
begin
Art:=pmNotCopy;
B_Normal.caption:='komplementär';
end

else
begin
  art:=pmCopy;
  B_Normal.caption:='normal';
end ;


end;



procedure TForm1.B_LoeschenClick(Sender: TObject);
begin
with Form1.Image1 do
  begin
  picture:=nil;
  end;
end;

end.