Why the flash occurs

In order to understand why the application does not minimize properly, we need to look into the MFC code that constructs and displays the main window. By placing a breakpoint in the ProcesShellCommand function, we see that, by default, the AppWnd OnFileNew handler is called. OnFileNew calls the CDocument* CDocument* CSingleDocTemplate::OpenDocumentFile(LPCTSTR lpszPathName,BOOL bMakeVisible) OpenDocument, which creates a new document instance, creates a new frame for the document, and finally displays the window by calling InitialUpdateFrame(pFrame, pDocument, bMakeVisible);, and displays the view and the mainframe window. The reason why the application does not display correctly when a different SW parameter is chosen instead of SW_SHOW, is because InitialUpdateFrame CFrameWnd::ActivateFrame() calls ShowWindow during the initialization of the window in the function. This implies that the call to ShowWindow in InitInstance() is redundant and not needed.

The solution

There are two solutions that can be used to solve the flashing problem. The first solution is to make a subclass of the SingleDocumentTemplate and call our derived version of OpenDocument with bMakeVisible = false for the minimized case. This, however, does not solve the case of using SW_MAXMIMIZE. Another solution, which is far more simpler and can be used for any ShowWIndow mode, is to set the application ShowWindow property prior to initializing the window, as shown below:

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        CSingleDocTemplate * pDocTemplate;
pDocTemplate = new CSingleDocTemplate (
RUNTIME_CLASS(CMainFrame),       // main SDI frame window
// Parse command line for standard shell commands, DDE, file open
CCommandLineInfo cmdInfo;
// Add the following line:
// Set the initial window display to whatever mode you like
this->m_nCmdShow = SW_MAXIMIZE;
// Dispatch commands specified on the command line
if (!ProcessShellCommand(cmdInfo))
return FALSE;
// The following line should be deleted since it is not needed 
// for a SDI application that used MFC The one and only window has
// been initialized, so show and update it.
return TRUE;

One may ask if the ShowWindow() line in the InitInstance has no purpose, and why Microsoft put that line there in the first place. The answer is, if one decides to construct an SDI application using the MFC application wizard and checks the option not to use MFC, this line is required to show the window. However, Microsoft should have deleted this line if MFC is used. However, since the vast majority of applications initially display ShowWindow with the SW_SHOW parameter, calling ShowWindow twice (the first time in ActivateFrame, as described above) will not influence the display of the application.