bootstrap的Modal和select2联合使用时，出现z-index层级问题

$(".select2-demo").select2({
    dropdownParent:$("#Modal-demo")
});

.select2-drop {
        z-index: 10050 !important;
    }
 
    .select2-search-choice-close {
        margin-top: 0 !important;
        right: 2px !important;
        min-height: 10px;
    }
 
        .select2-search-choice-close:before {
            color: black !important;
        }
    /*防止select2不会自动失去焦点*/
    .select2-container {
        z-index: 16000 !important;
    }
 
    .select2-drop-mask {
        z-index: 15990 !important;
    }
 
    .select2-drop-active {
        z-index: 15995 !important;
    }