Why I'm unable to click a control?

Hi,

You are confusing addressing the object by the alias and by the full name.

You cannot use ...["DocumentViewer"]["m_thumbnails"]["ListBoxItem","",1]["Click"], because ["ListBoxItem"] is the alias that is used to address your object in the test, and you cannot specify the index for the alias. You can specify the index if you address the object by the full name: ...["WPFObject"]("DocumentViewer")["WPFObject"]("m_thumbnails")["WPFObject"]("ListBoxItem","",1) (you can see the full name in the Object Browser panel).

So, to click the needed list box item, use the following statement:

Aliases["FusionDesktop"]["HwndSource_MainWindow"]["MainWindow"]["Grid"]["TabControl"]["Grid"]["ContentPanel"]["PART_SelectedContentHost"]["AssemblyViewTabControl"]["Grid"]["Grid1"]["UserControl"]["ScrollableTabControlScreen"]["DockPanel"]["ContentControl"]["DocumentViewer"]["m_thumbnails"]["ListBoxItem"]["Click"]

In order for TestComplete to click the item that has the index 1, you need to add the Index property to the set of identification properties of the mapped object that has the ListBoxItem alias. For more information, please refer to http://support.smartbear.com/viewarticle/11327/ and http://support.smartbear.com/viewarticle/12451/.

As for the message about an overlapped window, could you please clarify when this message appears?