Thanks for using Syncfusion products.
We would like to let you know that, the Dropdownlist gets focused when the user presses the tab key inside of the second input element. When the dropdownlist is in focus it gets highlighted with the shadow around it. Since the dropdownlist is not in editable state we have to change the input item by pressing up arrow key or down arrow key. So that we can select the items in the dropdownlist.
For your convenience we have prepared the sample and you can download the same under the following location.
Sample Location: Sample
Please let us know if you have further concern.