DUI: Library list is getting refreshed on adding an item

# Preface
Steps to reproduce:
1. Open Core > List > Click on actions > more button
2. Now click on "List.Create" under Create category to add a node
3. The list is reset to query. 

The list should remain where the user left it to be

# Solution
The easiest one :D

Reviewers
@Benglin, please take a look.

Link to YouTrack:
[MAGN-4688 DUi: Library list is getting refreshed on adding an item](http://adsk-oss.myjetbrains.com/youtrack/issue/MAGN-4688)

Nice, I think you need to change it this way?

```cs
if (searchElement != null)
{
    searchElement.Execute();
    e.Handled = true;
}
```