动态生成frame时需要对frame类进行注册，否则会出现找不到frame类的错误。

procedure TMainForm.openFram(Caption, FormClassName, imgIdx: string);
var
i: integer;
sheet: TUniTabSheet;
FCurrentFrame: TUniFrame;
begin
for i := 0 to page.PageCount - 1 do
begin
if page.Pages[i].Caption = Caption then
begin
page.ActivePageIndex := i;
exit;
end;
end;
sheet := TUniTabSheet.Create(Self);
sheet.Closable := True;
sheet.Caption := Caption;
sheet.ImageIndex := strToint(imgIdx);
sheet.PageControl := page;
sheet.Layout := 'fit';
FCurrentFrame := TUniFrameClass(FindClass(FormClassName)).Create(Self);
FCurrentFrame.Align := alClient;
FCurrentFrame.Parent := sheet;
page.ActivePage := sheet;
end;

需要加上这一段代码：
initialization
   RegisterClass(FormClassName);