BUG: GetWindowContextHelpId() returns 0 for ActiveX Controls

• The Microsoft Foundation Classes (MFC) included with: - Microsoft Visual C++, 32-bit Editions, versions 4.2, 4.2b, 5.0

SYMPTOMS

You can specify a control's help context ID by selecting the "Help ID" check box from the General tab of the control dialog box in resource editor. If the "Help ID" check box is selected, calling GetWindowContextHelpId() at runtime retrieves the help context identifier associated with the control. This works for all standard controls, such as edit controls, button controls, etc. However, for ActiveX controls, such as TestHelp controls, Circ3 controls, etc., 0 is returned.

CAUSE

MFC fails to associate a help context id for ActiveX controls even though the "Help ID" check box is selected.

RESOLUTION

When you call SetWindowContextHelpId() on the control with the correct ID, it sets the Help ID for the control. OnInitDialog is a good place to do this. For form views, OnInitialUpdate would be the best place to set the help ID. The sample code below shows a way to set and retrieve the help context ID of an ActiveX control (TestHelp control) in a CDialog-derived class.

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.

REFERENCES

Sample Code

   ...
   #include "resource.hm" // Make sure you include the .hm file
                          // generated by the resource editor
                          // It includes the help ID's for the
                          // controls.
   ...

   BOOL CMyDialog::OnInitDialog()
   {
       CDialog::OnInitDialog();

       ...
       // Associate a help context id with the TestHelp control.
       // IDC_TESTHELP_CONTROL is the id of the TestHelp control and
       // HIDC_TESTHELP_CONTROL is its help context id defined in
       // resource.hm file.
       CWnd* control = GetDlgItem(IDC_TESTHELP_CONTROL);
       control->SetWindowContextHelpId(HIDC_TESTHELP_CONTROL);

       return TRUE;  // return TRUE unless you set the focus to a control
                     // EXCEPTION: OCX Property Pages should return FALSE
   }

   void CMyDialog::MyFunction()
   {
       // Retrieve the help context id associated with the TestHelp
       // control.
       CWnd* control = GetDlgItem(IDC_TESTHELP_CONTROL);
       DWORD help_id = control->GetWindowContextHelpId();
       TRACE("Help ID for Control IDC_TESTHELP_CONTROL : %x\n", help_id);
       ...
   }