<wj-combo-box id="theCombo" [displayMemberPath]="'country'" [itemsSource]="data" (initialized)="initCombo(combo)" #combo>
 </wj-combo-box>

initCombo(combo: any){
    window['cb'] = combo;

     combo.hostElement.addEventListener('mousedown', (e) => {
         e.preventDefault()
         combo.isDroppedDown = !combo.isDroppedDown; //dropdown 보여주기
         combo.inputElement.setSelectionRange(combo.inputElement.selectionEnd, combo.inputElement.selectionEnd); // 셀 전체선택 블록 없애기
         combo.dropDown.focus(); //콤보박스 드롭다운에 포커스
    }, true)
}