title: Using IFileOpenDialog, with file extension filter for view/browse; how can that _also_ be applied to filter any "autosuggest" files?
body: <p>I am using a Win32 app with MFC in C++ and utilizing Forms with a series of Dialog Screens. My problem is, each of these utilizes the <code>IFileOpenDialog</code>, using <code>SetFileTypes()</code> to set the file extension filter by setting <code>COMDLG_FILTERSPEC</code>.  This has worked perfectly for years to limit the view in browser to just the root/basename of the file.</p>
  <p>However, recently it's been discovered that the user can type in the file name <code>combobox</code> in the File Open (Explorer Style) Dialog, and the &quot;autosuggest&quot; lists files <em>regardless</em> of extension.  The user may then select from the auto-suggest an un-filtered file extension, which is returned as &quot;legal&quot; (though it should be an illegal selection).  It seems the <code>_FILEOPENDIALOGOPTIONS</code> could be used with the <code>FOS_STRICTFILETYPES</code> set, except that (according to <a href="https://docs.microsoft.com/en-us/windows/win32/api/shobjidl_core/ne-shobjidl_core-_fileopendialogoptions" rel="nofollow noreferrer">MS documentation</a>) only applies exclusively to &quot;SaveDialog&quot;, and not &quot;OpenDialog&quot; scenarios.</p>
  <p>Is there a simple way (some other parameter or configuration setting) to force the file extension filter to apply to the AutoSuggest as well ?  Or to limit the legal selectable/return selection to the specified file extension ?</p>