QuickReport: OnPreview

OnPreview
procedure TQuickReport2.QuickRepPreview(Sender: TObject);
begin
    Form1.QRPreview1.QRPrinter := TQRPrinter(Sender);
end;

Button Show

procedure TForm1.Button1Click(Sender: TObject);
begin
  QuickReport2.PreviewModeless;
end;

Button Hidden

procedure TForm1.Button2Click(Sender: TObject);
begin
  QRPreview1.QRPrinter.ClosePreview(Self)
end;