PRB: ATL Controls Fail to Recognize Default Button on VB Form

• The Microsoft Active Template Library (ATL), versions 2.0, 2.1, 3.0, included with:
  • Microsoft Visual C++, 32-bit Editions, versions 5.0, 6.0

SYMPTOMS

When an ATL-based ActiveX control has the focus on a Visual Basic form, it does not give the focus to the default button on the form (the button with a Default property of True) when you press ENTER.

Steps to Reproduce Behavior

1. Add an ActiveX control that was written in ATL to a Visual Basic form.



2. Add a Command button to the form. Set the Default property to True.



3. Add an ActiveX control that was not written in ATL to the form.



4. Implement the Click event for the Command button as follows:

   
         Private Sub Command1_Click()
            MsgBox "Hello from Command1"
         End Sub 




5. Run the form. Select the ActiveX control that was not written in ATL and press ENTER. This causes the default Command button to activate and the message box appears.



6. Select the ATL-based control and press ENTER. The Command button does not get activated and the message box does not appear.

CAUSE

The reason for this behavior is that the default implementation in ATL of the IOleControlImpl::GetControlInfo() and IOleInPlaceActiveObjectImpl::TranslateAccelerator() methods just returns E_NOTIMPL. The container calls GetControlInfo to get the control's keyboard mnemonics and keyboard behavior, and it calls TranslateAccelerator() to process the keys.

RESOLUTION

Because the implementation in ATL of these IOleControlImpl-based methods simply returns E_NOTIMPL, the control writer must override these methods in the control class.

STATUS

Microsoft is researching this problem and will post new information here in the Microsoft Knowledge Base as it becomes available.

MORE INFORMATION

To override this behavior implement IOleControlImpl::GetControlInfo() and IOleInPlaceActiveObjectImpl::TranslateAccelerator() in your control class as shown below:

Sample Code

   STDMETHOD(GetControlInfo)(CONTROLINFO *pCI)
   {
      if(!pCI)
      {
         return E_POINTER;
      }
      pCI->hAccel   = NULL;
      pCI->cAccel   = 0;
      pCI->dwFlags  = 0;

      return S_OK;
   }

   STDMETHOD(TranslateAccelerator)(MSG *pMsg)
   {
      if (
         ((pMsg->message >= WM_KEYFIRST) && (pMsg->message <= WM_KEYLAST))
         &&
         ((VK_TAB == pMsg->wParam) || (VK_RETURN == pMsg->wParam))
      )
      {
         CComQIPtr<IOleControlSite,&IID_IOleControlSite>
         spCtrlSite(m_spClientSite);
         if(spCtrlSite)
         {
            return spCtrlSite->TranslateAccelerator (pMsg,0);
         }
      }
      return S_FALSE;
   } 

REFERENCES

Visual C++ Help; search on "IOleControl::GetControlInfo" and "IOleInPlaceActiveObject::TranslateAccelerator"

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

Q179696 PRB: Focus and Tab Issues with ATL Subclassed Edit Control

Additional query words: ATL Tabbing SubEdit GetControlInfo TranslateAccelerator IOleControl IOleControlImpl kbATL200 kbATL210 kbCtrl kbVC500 kbDSupport kbdsd kbatl300 kbvc600

Keywords : kbcode kbActiveX kbATL200 kbATL210 kbCOMt kbCtrlCreate kbKeyAccel kbVBp kbVC500 kbVC600 kbATL300 kbGrpMFCATL
Version : WINDOWS:2.0,2.1,3.0
Platform : WINDOWS
Issue type : kbprb