The dropdown tree is very useful. 

I have a suggestion to improve this, which would be highly appreciated by my customers:

Add a suggest possibility, the same as the suggest possibility that already is available on the combobox.

People start to type in the search box, most of time finding the one option they need, than they first have to select the option (mouse or arrows, plus enter). It would be nice if the result (when it is one result) is already selected and they should have only to press enter.