Mengubah warna komponen aktif

unit Unit1; interface uses   Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,   Dialogs, StdCtrls; type   TForm1 = class(TForm)     Edit1: TEdit;     Edit2: TEdit;     Edit3: TEdit;     Edit4: TEdit;     Edit5: TEdit;     procedure FormCreate(Sender: TObject);     procedure FormClose(Sender: TObject; var Action: TCloseAction);   private     procedure DoActiveControl(Sender: TObject);     { Private declarations }   public     { Public declarations }   end; var   Form1: TForm1;   OldControl: TComponent; implementation {$R *.dfm} procedure TForm1.DoActiveControl(Sender: TObject); begin   if assigned(OldControl) then   begin     (OldControl as TEdit).color := clWhite;     (OldControl as TEdit).font.color := clBlack;   end;   if activeControl is TEdit then   begin     (activeControl as TEdit).color := clRed;     (activeControl as TEdit).font.color := clYellow;     OldControl := activeControl as TEdit;   end; end; procedure TForm1.FormCreate(Sender: TObject); begin   screen.OnActiveControlChange := DoActiveControl; end; procedure TForm1.FormClose(Sender: TObject; var Action: TCloseAction); begin   // mencegah terjadinya GP Fault   screen.OnActiveControlChange := nil end; end.