FIX: F1 Help Routed Wrongly for Additional Top-Level Windows

MORE INFORMATION

When you press the F1 key, an ID_HELP command message is generated and is usually routed and handled in the application's main frame message map using CFrameWnd::OnHelp(). Then, the OnHelp functions (CFrameWnd and CWnd) finds the active window using ::GetLastActivePopup(hWnd), thereby passing the handle to the application's main frame. Unfortunately, this only returns windows handles that are a descendant of hWnd. If another top-level window was active when you pressed the F1 key, the main frame window is still used and the subsequent WM_COMMANDHELP messages is never sent to the correct active window.

The sample code below fixes this bug by sending the message to the window with the current focus before going through the default MFC logic.

Sample Code

   ////////////////////////////////////// 
   // HEADER file
   class CMainFrame : public CMDIFrameWnd
   {
      afx_msg void OnHelp();
      ...

   ////////////////////////////////////// 
   // IMPLEMENTATION file
   #include "afxpriv.h"

   BEGIN_MESSAGE_MAP(CMainFrame, CMDIFrameWnd)
   ...
      ON_COMMAND(ID_HELP, CMainFrame::OnHelp)
   END_MESSAGE_MAP()

   void CMainFrame::OnHelp()
   {
      if (m_dwPromptContext != 0)
      {
         if (m_dwPromptContext !=
            HID_BASE_PROMPT + AFX_IDP_FAILED_TO_LAUNCH_HELP)
            AfxGetApp()->WinHelp(m_dwPromptContext);
         return;
      }

      // attempt to get help from whoever has the focus
      HWND hWnd = ::GetFocus();
      while (hWnd != NULL)
      {
         // attempt to process help
         if (::SendMessage(hWnd, WM_COMMANDHELP, 0, 0))
            return;

         // check next parent/owner in the parent/owner chain
         CWnd* pWnd = CWnd::FromHandlePermanent(hWnd);
         if (pWnd != NULL)
            hWnd = pWnd->GetOwner()->GetSafeHwnd();
         else
            // otherwise, return parent in the Windows sense
            hWnd = ::GetParent(hWnd);
      }
      CWnd::OnHelp();