Dim sFile As String
sFile = Application.GetOpenFilename("Files(*.txt),*.txt", , "Выбрать файл", , Files)

Option Explicit
'API declaration for the windows "Search Results" dialog
Private Declare Function ShellSearch& Lib "shell32.dll" _
        Alias "ShellExecuteA" (ByVal hwnd As Long, _
        ByVal lpOperation As String, _
        ByVal lpFile As String, ByVal lpParameters As String, _
        ByVal lpDirectory As String, _
        ByVal nShowCmd As Long)
        
Private Const SW_SHOWNORMAL = 1


Sub ShowWindowsSearchDialog_API()
'   Specified drive to Search
    Const szSDrive As String = "C:\"
    
    ShellSearch 0, "find", szSDrive, "", "", SW_SHOWNORMAL
End Sub

Private Declare Sub Sleep Lib "kernel32.dll" (ByVal dwMilliseconds As Long)
Public Sub ShowFilteredWindow()
    Const FolderPath As String = "c:\projects"
    Dim pShell As New Shell32.Shell
    Dim pWin As Object, shFolderView As Shell32.ShellFolderView
    Dim pFolder As Shell32.Folder3
    
    Set pFolder = pShell.Namespace(FolderPath)
    pShell.Explore FolderPath
    Sleep 200
    For Each pWin In pShell.Windows
        Set shFolderView = pWin.document
        'узкое место, такая папка в проводнике может быть открыта не один раз
        If shFolderView.Folder.Title = pFolder.Title Then
            shFolderView.FilterView "*.txt"
        End If
    Next
End Sub