Cannot scroll down with arrow keys if long list dropdown

[aaron170]

When we have long list in the dropdown and if we limit the height of the dropdown say around 300px, then we cannot scroll down with the arrow keydown event. The selection keeps going down but does not scroll the list in the display area.
After Edit in the CSS file:
.angucomplete-dropdown {
border-color: #ececec;
border-width: 1px;
border-style: solid;
border-radius: 2px;
width: 250px;
padding: 6px;
cursor: pointer;
z-index: 9999;
position: absolute;
margin-top: -6px;
background-color: #ffffff;
/* New added */
height:300px;
overflow: auto;
overflow-x: hidden;
}