class CMainDlg : public CDialogImpl<CMainDlg>
{
public:

	enum { IDD = IDD_MAINDLG };
	// разное....
	// ......


	HTREEITEM htiRoot;
};

LRESULT CMainDlg::OnInitDialog(UINT /*uMsg*/, WPARAM /*wParam*/, LPARAM /*lParam*/, BOOL& /*bHandled*/)
{
	WTL::CTreeViewCtrl tree;
	tree.Attach( GetDlgItem(IDC_TREE1) );
	htiRoot = tree.InsertItem( L"All Items", TVI_ROOT, TVI_LAST);
	// добавляю ещё итемы
	tree.Expand( htiRoot );
	tree.SetCheckState( htiRoot, TRUE );
	tree.Detach();
	return TRUE;
}

LRESULT CMainDlg::OnInitDialog(UINT /*uMsg*/, WPARAM /*wParam*/, LPARAM /*lParam*/, BOOL& /*bHandled*/)
{
	WTL::CTreeViewCtrl tree;
	tree.Attach( GetDlgItem(IDC_TREE1) );
	htiRoot = tree.InsertItem( L"All Items", TVI_ROOT, TVI_LAST);
	tree.Detach();

	// заводим будильник
	SetTimer(99, 250);

	return TRUE;
}

LRESULT CMainDlg::OnTimer(UINT /*uMsg*/, WPARAM wParam, LPARAM /*lParam*/, BOOL& /*bHandled*/)
{
	if( wParam != 99 ) return 0;
	KillTimer(99);
	WTL::CTreeViewCtrl tree;
	tree.Attach( GetDlgItem(IDC_TREE1) );
	tree.SetCheckState( htiRoot, TRUE );
	tree.Detach();
	return 0;
}