The CancelObjectSelect method has effect only if it is called during the ObjectSelect event. Use the CancelObjectSelect method to prevent opening or browsing for folder items being double clicked. By default, if a folder item is being double clicked, the folder gets browsed. If a file is being double clicked, nothing is happen.

The following VB sample prevents opening a zip file ( which is considered a folder item ):

Private Sub ExShellView1_ObjectSelect(ByVal Object As EXSHELLVIEWLibCtl.IExShellObject)
    If Object.Name Like "*.zip" Then
        ExShellView1.CancelObjectSelect
    End If
End Sub