How to automate file download window's "open with" option in internet explorer

<img src='https://i.stack.imgur.com/XJMJp.png'/>

Tried recursively find the window, but NO SUCCESS

FindTreeViewDescendants(elementNode)
{
 AutomationElement elementNode = TreeWalker.ControlViewWalker.GetFirstChild(targetTreeViewElement);

        while (elementNode != null)
        {
            // Test for the control patterns of interest for this sample.
            object objPattern;
            ExpandCollapsePattern expcolPattern;
            if (true == elementNode.TryGetCurrentPattern(ExpandCollapsePattern.Pattern, out objPattern))
            {
                expcolPattern = objPattern as ExpandCollapsePattern;
                if (expcolPattern.Current.ExpandCollapseState != ExpandCollapseState.LeafNode)
                {
                    ExpandCollapsePattern expandPattern = ((ExpandCollapsePattern)expcolPattern);
                    if (expandPattern.Current.ExpandCollapseState != ExpandCollapseState.Expanded)
                        expandPattern.Expand();
                }
            }
            TogglePattern togPattern;
            if (true == elementNode.TryGetCurrentPattern(TogglePattern.Pattern, out objPattern))
            {
                togPattern = objPattern as TogglePattern;
                TogglePattern expandPattern = ((TogglePattern)togPattern);
                if (expandPattern.Current.ToggleState != ToggleState.On)
                    expandPattern.Toggle();
            }
            InvokePattern invPattern;
            if (true == elementNode.TryGetCurrentPattern(InvokePattern.Pattern, out objPattern))
            {
                if (elementNode.Current.Name == "Open with")
                {
                    invPattern = objPattern as InvokePattern;
                    InvokePattern expandPattern = ((InvokePattern)invPattern);
                    expandPattern.Invoke();
                }
            }

            // Iterate to next element.
            // elementNode - Current element.
            // treeviewIndex - Index of parent TreeView.
            FindTreeViewDescendants(elementNode);
            elementNode = TreeWalker.ControlViewWalker.GetNextSibling(elementNode);