procedure TForm1.Edit1MouseMove(Sender: TObject; Shift: TShiftState; X,
  Y: Integer);
begin
label1.Caption := inttostr(length(edit1.SelText));
end;

procedure TForm1.Edit1KeyUp(Sender: TObject; var Key: Word;
  Shift: TShiftState);
begin
label1.Caption := inttostr(length(edit1.SelText));
end;