BUG: When you edit labels in a CTreeCtrl, you are unable to use ESC or ENTER to cancel or accept changes in Visual C++

RESOLUTION

For Visual C++ 4.xx and later, we can trap the ESC and ENTER keystroke messages in the PreTranslateMessage() function for all CFormView, CDialog (modal or modeless) and CPropertyPage (either in modal or modeless CPropertySheet) derived classes.

In the code below, m_TreeCtrl is a member variable of those derived classes and it is of CTreeCtrl data type, and CMyXxx can be any CFormView, CDialog, or CPropertyPage derived class.

   BOOL CMyXxx::PreTranslateMessage(MSG* pMsg)
   {
      // If edit control is visible in tree view control, when you send a
      // WM_KEYDOWN message to the edit control it will dismiss the edit
      // control. When the ENTER key was sent to the edit control, the
      // parent window of the tree view control is responsible for updating
      // the item's label in TVN_ENDLABELEDIT notification code.
      if (pMsg->message == WM_KEYDOWN &&
         pMsg->wParam == VK_RETURN || pMsg->wParam == VK_ESCAPE)
      {
         CEdit* edit = m_TreeCtrl.GetEditControl();
         if (edit)
         {
            edit->SendMessage(WM_KEYDOWN, pMsg->wParam, pMsg->lParam);
            return TRUE;
         }
      }
      // CXxxx can be a CFormView, Cdialog, or CPropertyPage class.
      return CXxxx::PreTranslateMessage(pMsg);
   }
				

For Visual C++ 2.xx, since PreTranslateMessage() is not called for modal CDialog-derived classes, the sample code above does not apply to the modal dialog and property page in a modal CPropertySheet derived class. In this situation, those keystroke messages can be trapped in the overridden OnOK() (for Enter key) and OnCancel() (for Esc key) functions in either CDialog or CPropertySheet derived-class. The sample code works fine even in the absence of both the OK and Cancel buttons from the dialog resource template.

Note It is too late to trap those keystroke messages in CPropertyPage's OnOK() and OnCancel() functions. Therefore, we have to do it in CPropertySheet-derived class.

A new member function called IsTreeCtrlEditMessage() is added to the CDialog or CPropertySheet derived-class. This function sends a WM_KEYDOWN message to the tree-view's edit control when it is the window with focus. And it is being called in both overridden OnOK() and OnCancel() functions. The CMyDxxx in the sample code below can either be a CDialog or a CPropertySheet derived-class. Note that the MODAL_PROPERTYSHEET constant is declared and used in IsTreeCtrlEditMessage() so the same code can be applied to both CDialog and CPropertySheet derived-classes.

   // Set MODAL_PROPERTYSHEET to 1 for modal CPropertySheet-derived class
   // and 0 for CDialog-derived class.
   #define MODAL_PROPERTYSHEET  1

   BOOL CMyDxxx::IsTreeCtrlEditMessage(WPARAM KeyCode)
   {
      BOOL       rvalue = FALSE;

      // pWnd is a pointer to either an active CPropertyPage of the modal
      // CPropertySheet or a modal CDialog object.
      CWnd*   pWnd = this;
   #if MODAL_PROPERTYSHEET
      pWnd = GetActivePage();
   #endif

      // IDC_TREECTRL is the ID of the tree view control.
      CTreeCtrl *treectrl = (CTreeCtrl *) pWnd->GetDlgItem(IDC_TREECTRL);
      if (!treectrl)
         return rvalue;

      // If the edit control of the tree view control has the input focus,
      // sending a WM_KEYDOWN message to the edit control will dismiss the
      // edit control.  When ENTER key was sent to the edit control, the
      // parentwindow of the tree view control is responsible for updating
      // the item's label in TVN_ENDLABELEDIT notification code.
      CWnd*  focus = GetFocus();
      CEdit* edit  = treectrl->GetEditControl();
      if ((CEdit *) focus == edit)
      {
         edit->SendMessage(WM_KEYDOWN, KeyCode);
         rvalue = TRUE;
      }
      return rvalue;
   }

   void CMyDxxx::OnOK()
   {
      // Do not dismiss the dialog object if ENTER key was sent to the tree
      // view's edit control.  You may call the CDialog::OnOK() function if
      // this is for CDialog.
      if (!IsTreeCtrlEditMessage(VK_RETURN))
         EndDialog(IDOK);
   }

   void CMyDxxx::OnCancel()
   {
      // Do not dismiss the dialog object if ESC key was sent to the tree
      // view's edit control.  You might call the CDialog::Cancel()
      // function if this is for CDialog.
      if (!IsTreeCtrlEditMessage(VK_ESCAPE))
         EndDialog(IDCANCEL);
   }