uses
  {...,} cxPC, dxTabbedMDI;

type
  TcxTabControlProperties = class(cxPC.TcxCustomTabControlProperties)
  published
    property OnDrawTabEx;
  end;

  TForm1 = class(TForm)
    dxTabbedMDIManager1: TdxTabbedMDIManager;
    procedure FormShow(Sender: TObject);
  private
    procedure DrawTabExEvent(AControl: TcxCustomTabControlProperties;
      ATab: TcxTab; Font: TFont);
  end;

implementation

procedure TForm1.FormShow(Sender: TObject);
begin
  TcxTabControlProperties(dxTabbedMDIManager1.TabProperties).OnDrawTabEx := DrawTabExEvent;
end;

procedure TForm1.DrawTabExEvent(AControl: TcxCustomTabControlProperties;
  ATab: TcxTab; Font: TFont);
begin
  if Assigned(dxTabbedMDIManager1.TabProperties.ActivePage) then
    if ATab.Index = dxTabbedMDIManager1.TabProperties.ActivePage.Index then
      Font.Style := Font.Style + [fsBold];
end;

uses
  {...,} cxPC, dxTabbedMDI;

type
  TcxTabControlProperties = class(cxPC.TcxCustomTabControlProperties)
  published
    property OnDrawTabEx;
  end;

  TForm1 = class(TForm)
    dxTabbedMDIManager1: TdxTabbedMDIManager;
    procedure FormShow(Sender: TObject);
  private
    procedure DrawTabExEvent(AControl: TcxCustomTabControlProperties;
      ATab: TcxTab; Font: TFont);
  end;

implementation

procedure TForm1.FormShow(Sender: TObject);
begin
  TcxTabControlProperties(dxTabbedMDIManager1.TabProperties).OnDrawTabEx := DrawTabExEvent;
end;

procedure TForm1.DrawTabExEvent(AControl: TcxCustomTabControlProperties;
  ATab: TcxTab; Font: TFont);
begin
  // Убираем унопку с первой вкладки при
  // dxTabbedMDIManager.TabProperties.CloseButtonMode =
  //   cbmActiveAndHoverTabs, cbmActiveTab, cbmEveryTab
  if ATab.Index = 0 then
    ATab.AllowCloseButton := False;
end;

// Способ первый
procedure TForm1.Button1Click(Sender: TObject);
begin
  ShowMessage(dxTabbedMDIManager1.ViewInfo.TabsViewInfo.Tabs.Count.ToString);
end;

// Способ второй
procedure TForm1.Button1Click(Sender: TObject);
begin
  ShowMessage(dxTabbedMDIManager1.ViewInfo.TabsViewInfo.ViewInfoCount.ToString);
end;

procedure TForm1.Button1Click(Sender: TObject);
begin
  ShowMessage(dxTabbedMDIManager1.ViewInfo.TabsViewInfo.Tabs.VisibleTabsCount.ToString);
end;