void CMainFrame::OnDropDown() { CString FileName; CMFCToolBarComboBoxButton* pComboButton = (CMFCToolBarComboBoxButton*) m_wndLoadFileBar.GetButton(1); CComboBox* pLoadFile = pComboButton->GetComboBox(); pLoadFile->GetWindowText(FileName); pLoadFile->ResetContent(); pLoadFile->Dir(DDL_READWRITE,"*.*"); pLoadFile->SetWindowText(FileName); }