BUG: ESC/ENTER Keys Don't Work When Editing CTreeCtrl Labels

• Microsoft Visual C++, 32-bit Editions, versions 2.0, 2.1, 2.2, 4.0, 4.0a, 4.1, 4.2, 4.2b, 5.0

SYMPTOMS

When you edit labels in a CTreeCtrl, you are allowed to press the ESC key to cancel the changes or press the ENTER key to accept the changes. However, when the CTreeCtrl is a child window of a dialog box (CDialog), a formview window (CFormView), or a property page (CPropertyPage), the ESC or ENTER keys do not function as expected.

CAUSE

IsDialogMessage() function is called in the PreTranslateInput() function which in turn is called in the PreTranslateMessage() function of all CFormView or CDialog derived classes mentioned above. The ESC and ENTER keys are processed in IsDialogMessage() but are not passed on to the edit control created by the tree-view control. Thus, these keystrokes have no effect.

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, sending a
      // WM_KEYDOWN message to the edit control will dismiss the edit
      // control.  When 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);
   }

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; 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 may call the CDialog::Cancel() function
      // if this is for CDialog.
      if (!IsTreeCtrlEditMessage(VK_ESCAPE))
         EndDialog(IDCANCEL);
   }

STATUS

Microsoft has confirmed this to be a bug in the Microsoft products listed at the beginning of this article. We are researching this bug and will post new information here in the Microsoft Knowledge Base as it becomes available.

MORE INFORMATION

For more information about CTreeCtrl, please refer to the MFC online help and Win32 SDK help files.

REFERENCES

For additional information, please see the following article in the Microsoft Knowledge Base:

   ARTICLE-ID: Q130691
   TITLE     : BUG: ESC/ENTER Keys Don't Work When Editing Labels in
               TreeView