function farbe(idx: integer): TColor; 
begin 
  case idx of 
    0: result := clred; 
    1: result := cllime; 
    2: result := clyellow; 
  else result := clBtnFace; 
  end; 
end; 
 
procedure flaeche(tc: TCustomTabcontrol); 
begin 
  with tc do 
    canvas.floodfill(3, height - 3, canvas.pixels[3, height - 3], fsSurface); 
end; 
 
procedure TForm1.FormCreate(Sender: TObject); 
begin 
  Tabcontrol1.ownerdraw := true; 
  Tabcontrol1.tabindex := 0; 
// und zum Testen: 
  TabControl1.Tabs.Add('Reiter1'); 
  TabControl1.Tabs.Add('Reiter2'); 
  TabControl1.Tabs.Add('Reiter3'); 
end; 
 
procedure TForm1.TabControl1Change(Sender: TObject); 
begin 
  TTabcontrol(sender).canvas.brush.color := 
    farbe(TTabcontrol(sender).tabindex); 
  flaeche(TTabcontrol(sender)); 
end; 
 
procedure TForm1.TabControl1DrawTab(Control: TCustomTabControl; 
  TabIndex: Integer; const Rect: TRect; Active: Boolean); 
var r: TRect; 
begin 
  with control.canvas do begin 
    brush.color := farbe(tabindex); 
    if tabindex = 0 then flaeche(control); 
    r := rect; 
    fillrect(rect); // Reiterfarbe 
    brush.style := bsclear; 
    inflaterect(r, 0, -2); 
    drawtext(handle, pchar(TTabControl(control).tabs[tabindex]), -1, r, 
      dt_center or dt_vcenter or dt_singleline); 
  end; 
end;