VB Forum / General 2 / September 2008

If they do that whatever app is selected will be started.  If it's your app
then a second instance of your app will start and Command$ will contain the
path to the selected file.

They're not actually selecting the file at that point, at least not as far
as the common dialog is concerned. If they right-clicked and chose Select,
then that would be equivalent clicking Open, but not using Open With. Open
With is provided by Windows Explorer, and it's as invisible to the common
dialog as, say, copy and paste.

The bottom line is: tell your user not to do that, or at least that it's not
something your app supports.

fwiw, the functionality you're describing is built in to the dialog and
every app using that dialog has the same limitations, regardless of which
language was used to write the app. You can probably setup a hooked dialog
to intercept this kind of thing, but constantly fighting the built in
behavior of any component, is an uphill battle.... the code below allows you
to completely replace the ocx you're using. It /probably/ traps right-click,
if you want it to, but I'm not sure.

CommonDialog/Direct
http://www.vbaccelerator.com/home/vb/code/Libraries/Common_Dialogs/Common_Dialog
_Direct/article.asp

<q>
There are a number of areas where Common Dialog/Direct improves upon the
implementation of COMDLG32.OCX supplied with VB:

Common Dialog hooks are supported. It is possible to:
  Confirm files being chosen before a file dialog is closed
  Centre dialogs accurately to any object
  Incorporate a common dialog into your own form, like the Add Form and New
Project dialogs in VB5.
  Templates are supported.

The file dialogs return the selected filter index when the user chooses a
file. You can get and set the custom colours set up in the colour dialog. It
is possible to show the Page Setup dialog for the printer
</q>

You'd have to use the GetOpenFileName API directly, set a callback hook to the
common dialog that results, and watch for CDN_SELCHANGE notifications.  Call
SendMessage with CDM_GETSPEC to get the filename:

     Case CDN_SELCHANGE
        ' Find handle to dialog window.
        hWnd = GetParent(hDlg)
        ' Get size of buffer required for filespec.
        nChars = SendMessage(hWnd, CDM_GETSPEC, 0&, ByVal m_FileEx)
        ' Get the full buffer for the filespec(s)
        If nChars > 0 Then
           m_FileEx = Space$(nChars)
           Call SendMessage(hWnd, CDM_GETSPEC, nChars, ByVal m_FileEx)
        End If

Optionally, test which mouse button is down at this point, to decide how to proceed.