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POWhat can cause Windows to send the ID_HELP command twice
 

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  1. POWhat can cause Windows to send the ID_HELP command twice
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    <p>In my app, I overrode <code>CFrameWnd::OnHelp</code> to open a word doc instead of our old .hlp file. However, when I press F1, I noticed the function is being executed twice. I examined the stacks and found that <code>AfxWndProcBase</code> is receiving command <code>0x1E146</code>, and then <code>CWnd::OnCommand</code> is truncating that to <code>0xE146</code> when calling <code>CFrameWnd::OnCmdMsg</code>, and <code>0xE146</code> is the <code>ID_HELP</code> command. Then immediately after this, <code>AfxWndProcBase</code> is receiving command <code>0xE146</code>, and runs the help command again. After some experimentation, I've discovered that the second message is being received and processed <em>inside</em> the call to <code>AfxMessageBox</code> when the first message is being processed.</p> <p>Handler is here:</p> <pre><code>void CMainFrame::OnHelp() { BOOL bWorked; STARTUPINFO suInfo = {}; suInfo.cb = sizeof(suInfo); PROCESS_INFORMATION procInfo = {}; CString m_Process = _T("Start"); CString vipx = /*_T("\"") +*/ CString(AfxGetApp()-&gt;m_pszHelpFilePath) /*+ _T("\"")*/; bWorked = ::CreateProcess(m_Process, vipx.GetBuffer(), // requires non-const :( NULL, NULL, FALSE, NORMAL_PRIORITY_CLASS, NULL, NULL, &amp;suInfo, &amp;procInfo); vipx.ReleaseBuffer(); if (procInfo.dwThreadId==NULL || bWorked==false) AfxMessageBox(_T("Failed to launch help: " + GetErrNoText(GetLastError()))); //AfxMessageBox causes my app to receive the message again? CloseHandle(procInfo.hProcess); CloseHandle(procInfo.hThread); } </code></pre> <p>Why are both <code>0x1E146</code> and <code>0xE146</code> being sent to my app when I press F1 (and what is the first one?)</p> <p>After a rewrite, I discovered that calling <code>ShellExecute</code> also causes the "1 deep recursion".</p> <p>I have no idea if it's relevent, but here's my form's message map:</p> <pre><code>BEGIN_MESSAGE_MAP(CMainFrame, CFrameWnd) //{{AFX_MSG_MAP(CMainFrame) ON_WM_CREATE() //}}AFX_MSG_MAP // Global help commands ON_COMMAND(ID_HELP, OnHelp) //F1 &lt;--- both messages are this one? END_MESSAGE_MAP() </code></pre> <p>In my resource file I found these, one for F1 and one for Shift+F1:</p> <pre><code>VK_F1, ID_CONTEXT_HELP, VIRTKEY, SHIFT, NOINVERT VK_F1, ID_HELP, VIRTKEY, NOINVERT </code></pre> <p>Probably useless, but here's the two callstacks:</p> <pre><code>MyApp.exe!CMainFrame::OnHelp() Line 66 C++ mfc90ud.dll!_AfxDispatchCmdMsg(CCmdTarget * pTarget=0x01fea410, unsigned int nID=57670, int nCode=0, void (void)* pfn=0x0040b720, void * pExtra=0x00000000, unsigned int nSig=57, AFX_CMDHANDLERINFO * pHandlerInfo=0x00000000) Line 82 C++ mfc90ud.dll!CCmdTarget::OnCmdMsg(unsigned int nID=57670, int nCode=0, void * pExtra=0x00000000, AFX_CMDHANDLERINFO * pHandlerInfo=0x00000000) Line 381 + 0x27 bytes C++ mfc90ud.dll!CFrameWnd::OnCmdMsg(unsigned int nID=57670, int nCode=0, void * pExtra=0x00000000, AFX_CMDHANDLERINFO * pHandlerInfo=0x00000000) Line 946 + 0x18 bytes C++ mfc90ud.dll!CWnd::OnCommand(unsigned int wParam=123206, long lParam=0) Line 2364 C++ mfc90ud.dll!CFrameWnd::OnCommand(unsigned int wParam=123206, long lParam=0) Line 366 C++ mfc90ud.dll!CWnd::OnWndMsg(unsigned int message=273, unsigned int wParam=123206, long lParam=0, long * pResult=0x0018fba4) Line 1769 + 0x1e bytes C++ mfc90ud.dll!CWnd::WindowProc(unsigned int message=273, unsigned int wParam=123206, long lParam=0) Line 1755 + 0x20 bytes C++ mfc90ud.dll!AfxCallWndProc(CWnd * pWnd=0x01fea410, HWND__ * hWnd=0x001703da, unsigned int nMsg=273, unsigned int wParam=123206, long lParam=0) Line 240 + 0x1c bytes C++ mfc90ud.dll!AfxWndProc(HWND__ * hWnd=0x001703da, unsigned int nMsg=273, unsigned int wParam=123206, long lParam=0) Line 403 C++ mfc90ud.dll!AfxWndProcBase(HWND__ * hWnd=0x001703da, unsigned int nMsg=273, unsigned int wParam=123206, long lParam=0) Line 441 + 0x15 bytes C++ ... mfc90ud.dll!CFrameWnd::PreTranslateMessage(tagMSG * pMsg=0x00712740) Line 249 + 0x1b bytes C++ mfc90ud.dll!CWnd::WalkPreTranslateTree(HWND__ * hWndStop=0x00160bb4, tagMSG * pMsg=0x00712740) Line 2946 + 0x14 bytes C++ mfc90ud.dll!AfxInternalPreTranslateMessage(tagMSG * pMsg=0x00712740) Line 233 + 0x12 bytes C++ mfc90ud.dll!CWinThread::PreTranslateMessage(tagMSG * pMsg=0x00712740) Line 777 + 0x9 bytes C++ MyApp.exe!CCXMyAppApp::PreTranslateMessage(tagMSG * pMsg=0x00712740) Line 749 C++ mfc90ud.dll!AfxPreTranslateMessage(tagMSG * pMsg=0x00712740) Line 252 + 0x11 bytes C++ mfc90ud.dll!AfxInternalPumpMessage() Line 178 + 0x18 bytes C++ </code></pre> <p>Second message:</p> <pre><code>MyApp.exe!CMainFrame::OnHelp() Line 66 C++ mfc90ud.dll!_AfxDispatchCmdMsg(CCmdTarget * pTarget=0x01fea410, unsigned int nID=57670, int nCode=0, void (void)* pfn=0x0040b720, void * pExtra=0x00000000, unsigned int nSig=57, AFX_CMDHANDLERINFO * pHandlerInfo=0x00000000) Line 82 C++ mfc90ud.dll!CCmdTarget::OnCmdMsg(unsigned int nID=57670, int nCode=0, void * pExtra=0x00000000, AFX_CMDHANDLERINFO * pHandlerInfo=0x00000000) Line 381 + 0x27 bytes C++ mfc90ud.dll!CFrameWnd::OnCmdMsg(unsigned int nID=57670, int nCode=0, void * pExtra=0x00000000, AFX_CMDHANDLERINFO * pHandlerInfo=0x00000000) Line 946 + 0x18 bytes C++ mfc90ud.dll!CWnd::OnCommand(unsigned int wParam=57670, long lParam=0) Line 2364 C++ mfc90ud.dll!CFrameWnd::OnCommand(unsigned int wParam=57670, long lParam=0) Line 366 C++ mfc90ud.dll!CWnd::OnWndMsg(unsigned int message=273, unsigned int wParam=57670, long lParam=0, long * pResult=0x0018e264) Line 1769 + 0x1e bytes C++ mfc90ud.dll!CWnd::WindowProc(unsigned int message=273, unsigned int wParam=57670, long lParam=0) Line 1755 + 0x20 bytes C++ mfc90ud.dll!AfxCallWndProc(CWnd * pWnd=0x01fea410, HWND__ * hWnd=0x001703da, unsigned int nMsg=273, unsigned int wParam=57670, long lParam=0) Line 240 + 0x1c bytes C++ mfc90ud.dll!AfxWndProc(HWND__ * hWnd=0x001703da, unsigned int nMsg=273, unsigned int wParam=57670, long lParam=0) Line 403 C++ mfc90ud.dll!AfxWndProcBase(HWND__ * hWnd=0x001703da, unsigned int nMsg=273, unsigned int wParam=57670, long lParam=0) Line 441 + 0x15 bytes C++ ... mfc90ud.dll!CWnd::SendMessageW(unsigned int message=273, unsigned int wParam=57670, long lParam=0) Line 42 + 0x44 bytes C++ mfc90ud.dll!CWnd::OnHelpInfo(tagHELPINFO * __formal=0x0008c890) Line 3195 C++ mfc90ud.dll!CWnd::OnWndMsg(unsigned int message=83, unsigned int wParam=0, long lParam=575632, long * pResult=0x0018e5ec) Line 1948 + 0xd bytes C++ mfc90ud.dll!CWnd::WindowProc(unsigned int message=83, unsigned int wParam=0, long lParam=575632) Line 1755 + 0x20 bytes C++ mfc90ud.dll!AfxCallWndProc(CWnd * pWnd=0x0253a410, HWND__ * hWnd=0x00160bb4, unsigned int nMsg=83, unsigned int wParam=0, long lParam=575632) Line 240 + 0x1c bytes C++ mfc90ud.dll!AfxWndProc(HWND__ * hWnd=0x00160bb4, unsigned int nMsg=83, unsigned int wParam=0, long lParam=575632) Line 403 C++ mfc90ud.dll!AfxWndProcBase(HWND__ * hWnd=0x00160bb4, unsigned int nMsg=83, unsigned int wParam=0, long lParam=575632) Line 441 + 0x15 bytes C++ ... mfc90ud.dll!CWnd::DefWindowProcW(unsigned int nMsg=83, unsigned int wParam=0, long lParam=575632) Line 1043 + 0x20 bytes C++ mfc90ud.dll!CWnd::Default() Line 274 C++ mfc90ud.dll!CWnd::OnHelpInfo(tagHELPINFO * __formal=0x0008c890) Line 3198 + 0x8 bytes C++ mfc90ud.dll!CWnd::OnWndMsg(unsigned int message=83, unsigned int wParam=0, long lParam=575632, long * pResult=0x0018eb70) Line 1948 + 0xd bytes C++ mfc90ud.dll!CWnd::WindowProc(unsigned int message=83, unsigned int wParam=0, long lParam=575632) Line 1755 + 0x20 bytes C++ mfc90ud.dll!AfxCallWndProc(CWnd * pWnd=0x0253aa28, HWND__ * hWnd=0x000b08c6, unsigned int nMsg=83, unsigned int wParam=0, long lParam=575632) Line 240 + 0x1c bytes C++ mfc90ud.dll!AfxWndProc(HWND__ * hWnd=0x000b08c6, unsigned int nMsg=83, unsigned int wParam=0, long lParam=575632) Line 403 C++ mfc90ud.dll!AfxWndProcBase(HWND__ * hWnd=0x000b08c6, unsigned int nMsg=83, unsigned int wParam=0, long lParam=575632) Line 441 + 0x15 bytes C++ ... mfc90ud.dll!CWnd::DefWindowProcW(unsigned int nMsg=77, unsigned int wParam=0, long lParam=0) Line 1043 + 0x20 bytes C++ mfc90ud.dll!CWnd::WindowProc(unsigned int message=77, unsigned int wParam=0, long lParam=0) Line 1756 + 0x1c bytes C++ mfc90ud.dll!AfxCallWndProc(CWnd * pWnd=0x0253aa28, HWND__ * hWnd=0x000b08c6, unsigned int nMsg=77, unsigned int wParam=0, long lParam=0) Line 240 + 0x1c bytes C++ mfc90ud.dll!AfxWndProc(HWND__ * hWnd=0x000b08c6, unsigned int nMsg=77, unsigned int wParam=0, long lParam=0) Line 403 C++ mfc90ud.dll!AfxWndProcBase(HWND__ * hWnd=0x000b08c6, unsigned int nMsg=77, unsigned int wParam=0, long lParam=0) Line 441 + 0x15 bytes C++ ... mfc90ud.dll!CWnd::WindowProc(unsigned int message=7423648, unsigned int wParam=7423712, long lParam=2016221872) Line 1755 + 0x20 bytes C++ ... mfc90ud.dll!AfxDeactivateActCtx(unsigned long dwFlags=0, unsigned long ulCookie=353633777) Line 260 + 0x17 bytes C++ mfc90ud.dll!AFX_MAINTAIN_STATE2::~AFX_MAINTAIN_STATE2() Line 63 + 0xe bytes C++ </code></pre>
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      1. VTUpMod
    1. CO`CWnd::OnCommand` truncates `wParam` 0x1E146 to `nID` 0xE146 because `nID = LOWORD(wParam)`, so that's ok. Do you get two messages if you replace `AfxMessageBox` by `TRACE`? Also, I don't understand the "+" in the call to `AfxMessageBox`, parameter #1 is a LPCTSTR, so you would need to concatenate the strings before calling `AfxMessageBox`, that would not happen with a "+"
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      1. POWhat can cause Windows to send the ID_HELP command twice
      1. USEdward Clements
    2. COI haven't tried a `TRACE`, but if I call `ShellExecute` before the `AfxMessageBox`, _that_ gets the second message _instead_. Very bizarre. `GetErrNoText` is a function I wrote that returns a `CString`, so `LPCTSTR+CString` does indeed concatenate.
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      1. POWhat can cause Windows to send the ID_HELP command twice
      1. USMooing Duck
 

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