Bootstrap模态框Modal添加鼠标拖动支持

<div class="modal fade" id="modal_config_form" data-backdrop="static" data-keyboard="false">
    <div class="modal-dialog" style="width:600px;height:400px;">
        <div class="modal-content" style="height:100%;">
            <div class="modal-header">
                <h5 class="modal-title" id="exampleModalLabel">插件配置</h5>
                <button type="button" class="close" data-dismiss="modal" aria-label="Close">
                    <span aria-hidden="true">&times;</span>
                </button>
            </div>

            <div class="modal-body gz-layout">
                <div class="gz-layout-item" style="overflow:auto;">
                    <div id="configFormContain"></div>
                </div>
            </div>
            <div class="modal-footer">
                <button type="button" class="btn btn-secondary" data-dismiss="modal">关闭</button>
                <button class="btn btn-primary" id="btn_SaveConfig">确定</button>
            </div>
        </div>
    </div>
</div>

 $(document).on("show.bs.modal", ".modal", function () {
    $('.modal-dialog').draggable({
        connectToSortable: ".modal.fade",
        drag:function(event,ui){
            // 最大横坐标
            var _x_max=window.innerWidth-ui.helper.width()-parseInt(ui.helper.css("margin-left"))
            // 最大纵坐标
            var _y_max =window.innerHeight-ui.helper.height()-parseInt(ui.helper.css("margin-top"));
            // 最小横坐标
            var _x_min=parseInt(ui.helper.css("margin-left"))*-1
            // 最小纵坐标
            var _y_min = parseInt(ui.helper.css("margin-top"))*-1

            if(ui.offset.left<_x_min){
                ui.offset.left=_x_min;
                ui.position.left=_x_min;
            }

            if(ui.offset.top<_y_min){
                ui.offset.top=_y_min;
                ui.position.top=_y_min;
            }


            if(ui.offset.top>_y_max){
                ui.offset.top=_y_max;
                ui.position.top=_y_max;

            }
            if(ui.offset.left>_x_max){
                ui.offset.left=_x_max;
                ui.position.left=_x_max;
            }

        }
    });
    $(this).css("overflow", "hidden");
    // 不拖动透明背景
});