.
.
.
type
TForm1 = class(TForm)
Edit1: TEdit;
Edit2: TEdit;
Button1: TButton;
Button2: TButton;
procedure Enter(Sender: TObject);
procedure Exit(Sender: TObject);
.
.
.

procedure TForm1.Enter(Sender: TObject);
begin
if (Sender is TCustomEdit) then TEdit(Sender).Color := clRed;
if (Sender is TButton) then TButton(Sender).Font.Style := [fsBold];
end;

procedure TForm1.Exit(Sender: TObject);
begin
if (Sender is TCustomEdit) then TEdit(Sender).Color := clWindow;
if (Sender is TButton) then TButton(Sender).Font.Style := [];
end;