Repro steps:

Mouse cursor is kept always over the component.

1. Starting point shows top item highlighted

2. Use down arrow key to move beyond the last item shown in the select box. (The mouse cursor is still over the component.

Expected behavior even with the mouse over the component:

1. Starting point shows top item highlighted.

2. Use down arrow key to move beyond the last item shows in the select box.

The item past the last item was ZuluSilver5, which is now highlighted.