procedure Memo_DateOnBeforePrint(Sender: TfrxComponent);
begin
  if (Get('date') = '01.01.1900') then begin
    Memo_Date.Visible := False;                                                            
  end else begin
    Memo_Date.Visible := True;    
  end;
end;

procedure Click;
var p: TfrxPage;
    i: integer;
    s: string;
begin
  with frxPreview1 do begin
    P := PreviewPages.Page[PageNo - 1];
    if p = nil then exit;

    for i := 0 to p.AllObjects.Count - 1 do
      if TObject(p.AllObjects.Items[i]) is TfrxMemoView then
        with TfrxMemoView(p.AllObjects.Items[i]) do
         if Name = 'Memo_Date' then begin
           if SpecialMode then begin
             Text := '01.01.1900';
             Visible := False;
           end else begin
             Text := FormatDateTime('dd.mm.yyyy', currDate);
             Visible := True;
           end;
         end;

         TfrxMemoView(DatabaseF.frxReport1.FindObject('Memo_Date')).BeforePrint;
    try
      Lock;
      PreviewPages.ModifyPage(PageNo - 1, TfrxReportPage(p));
    finally
      Unlock;
    end;
  end;
end;