BUG: BN_DOUBLECLICKED Message Handler Not Hit in MFC Dialog Box

• Microsoft Windows CE Toolkit for Visual C++ 6.0, used with:
  • The Microsoft Foundation Classes (MFC)

SYMPTOMS

On Windows CE using the MFC classes, when you add a BN_DOUBLECLICKED message handler for a button on a dialog box or a window, the handler is not called when the button is double-clicked. The handler is called on Microsoft Windows 95, Microsoft Windows 98, Microsoft Windows NT 4.0, and Microsoft Windows 2000.

CAUSE

This problem is due to a bug in the Windows CE operating system.

RESOLUTION

One possible resolution is to add a BN_CLICKED handler for the button. Inside of the handler, use code similar to the following to test whether the button has been clicked in the last few milliseconds:

  static BOOL s_bLastClicked = TRUE;
  static DWORD s_dwTickCount = 0;
  if (s_bLastClicked)
  {
    DWORD dwTickCount = GetTickCount();
    if ((dwTickCount - s_dwTickCount) < 500) //Last click less than 500ms?
    {
      s_bLastClicked = FALSE; //Was double-clicked, don't test next time...

      //Assume a double click...
      //Do your double-click code here...
    }
    s_dwTickCount = dwTickCount;
  }
  else
     s_bLastClicked = TRUE; 

STATUS

Microsoft has confirmed this to be a bug in the Microsoft products listed at the beginning of this article.

MORE INFORMATION

Steps to Reproduce Behavior

1. Create a new dialog-based application by using the WCE MFC AppWizard. Accept all of the default values and click Finish.



2. In the OnInitDialog method, add the following code before the return statement:

   SetClassLong(m_hWnd, GCL_STYLE, GetClassLong(m_hWnd, GCL_STYLE) | CS_DBLCLKS); 




3. Add a button to the dialog box. Right-click the button and click Properties. Click the Styles tab and select the Notify check box.



4. Use ClassWizard by clicking the View menu and selecting the menu item ClassWizard. Under the Object IDs section, click IDC_BUTTON1. Under the Messages section, click the BN_DOUBLECLICKED message. Click Add Function, and then click Edit Code.



5. Place a break point in the BN_DOUBLECLICKED message handler for the button.



6. Build the application and run it when done building.

Additional query words: CE specific double click WM_LBUTTONDBLCLK BN_CLICKED BN_DOUBLECLICKED WM_LBUTTONDOWN WM_LBUTTONUP

Keywords : kbButton kbMFC kbMouse kbVC600bug kbWinCE kbWndwMsg kbWinCE210bug kbDSupport kbGrpMFCATL
Version : WINDOWS:6.0
Platform : WINDOWS
Issue type : kbbug