点击不同按钮生成不同窗体到某个panel上面，类似Frame用法--不错

//点击不同按钮生成不同页面加载到某个panel上面。
procedure TMainForm.DemoButtonClick(Sender: TObject);
var
  NewDemoClass: TFormClass;  // TFormClass = class of TForm; 涉及到类的类 知识点； NewDemoClass表示为窗体类的类，有待考证

NewDemo: TForm; begin case (Sender as TSpeedButton).Tag of 0: NewDemoClass := TSpeedForm; //type  TSpeedForm = class(TForm)

    1:
      NewDemoClass := TGeneralForm;
    2:
      NewDemoClass := TPropertiesForm;
    3:
      NewDemoClass := TVisibilityForm;
    5:
      NewDemoClass := TGridForm;
    6: NewDemoClass := TDrawTreeForm;
    7:  NewDemoClass := TAlignForm;
    8:  NewDemoClass := TWindowsXPForm;
    9: NewDemoClass := TNodeForm;
    10:  NewDemoClass := THeaderOwnerDrawForm;
  else
    NewDemoClass := nil;
  end;
  if (ContainerPanel.ControlCount = 0) or not (ContainerPanel.Controls[0] is NewDemoClass) then //panel上没有或不是当前类时才可能创建。
  begin
    if ContainerPanel.ControlCount > 0 then
      ContainerPanel.Controls[0].Free;
    if Assigned(NewDemoClass) then
    begin
      NewDemo := NewDemoClass.Create(Self);//所属为self 指主窗体
      NewDemo.Hide;
      NewDemo.BorderStyle := bsNone;
      NewDemo.Parent := ContainerPanel; //显示的位置
      NewDemo.Align := alClient;
      NewDemo.Show;
    end;
  end;
end;