In order to make a UX component that is "keyboard friendly" (i.e. minimizes the need for the user to use the mouse to tap on a button to open a pick-list), the edit-combo control can be configured to open automatically as soon as the user tabs into the control, and then once the user makes a selection from the pick-list, you can set focus to the next control.

in this video we show how you can configure the edit-combo to behave in this "keyboard friendly" manner.