The CDialog class does not receive the WM_MOUSEWHEEL message on a Windows 95-based computer (237998)

RESOLUTION

1. Register the MSH_MOUSEWHEEL message. Copy the following line to your Dialog.cpp file:

   AFX_STATIC UINT _afxMsgMouseWheel =
     (((::GetVersion() & 0x80000000) && LOBYTE(LOWORD(::GetVersion()) == 4)) ||
     (!(::GetVersion() & 0x80000000) && LOBYTE(LOWORD(::GetVersion()) == 3)))
     ? ::RegisterWindowMessage(MSH_MOUSEWHEEL) : 0;
   						

2. Add this line to your dialog class' message map after the AFX_MSG_MAP section:

    ON_REGISTERED_MESSAGE(_afxMsgMouseWheel, OnRegisteredMouseWheel)
   						

3. Add a member function called OnRegisteredMouseWheel passing a WPARAM and LPARAM and returning LRESULT to your Dialog class. Add the following code in the function definition (code taken from Winfrm.cpp):

   LRESULT CMyDialog::OnRegisteredMouseWheel(WPARAM wParam, LPARAM lParam)
   {
    // Convert from MSH_MOUSEWHEEL to WM_MOUSEWHEEL.
   
      WORD keyState = 0;
      keyState |= (::GetKeyState(VK_CONTROL) < 0) ? MK_CONTROL : 0;
      keyState |= (::GetKeyState(VK_SHIFT) < 0) ? MK_SHIFT : 0;
   
      LRESULT lResult;
      HWND hwFocus = ::GetFocus();
      const HWND hwDesktop = ::GetDesktopWindow();
   
      if (hwFocus == NULL)
        lResult = SendMessage(WM_MOUSEWHEEL, (wParam << 16) | keyState, lParam);
      else
      {
         do {
            lResult = ::SendMessage(hwFocus, WM_MOUSEWHEEL,
                               (wParam << 16) | keyState, lParam);
            hwFocus = ::GetParent(hwFocus);
         }
         while (lResult == 0 && hwFocus != NULL && hwFocus != hwDesktop);
      }
      return lResult;
   }