bootstrap multi-select添加窗口水平滚动条

Question

Boostrap multiselect菜单在单击选择按钮时添加窗口滚动条 在菜单的最右侧放置多选，但期望下拉菜单按钮的位置自动调整，这不会发生，例如弹出窗口的方式。

$('.select').multiselect({ enableClickableOptGroups: true, includeSelectAllOption: true, onDropdownShown: function(event) { resetDropdownHeight(); } });

并尝试添加onDropdownShown事件，如下所示

function resetDropdownHeight(){
            $_dropdownMenu = $('select#testmodal').parent().find('ul');
            console.log(this);
             if ($_dropdownMenu !== null) {
                        $_dropdownMenu.css('left', '55%');
                        $_dropdownMenu.css('right', '5%');                                                                          
                    }


            }

下面是它的HTML

 <select multiple="multiple" id="testmodal" class="dropdown-lenthy subtypemultiple version-enableClickableOptGroups-disabled right-dropdown form-control col-md-12 col-sm-12 col-xs-12 firstdll dropdown-menu-right">

                                                            <option value="1-1">loremu test wright node care must thiis line to read content</option>
                                                            <option value="1-2">loremu test wright node care must thiis line to read content (with Lower/Upper Cap if any)</option>
                                                            <option value="1-3">loremu test wright node care must thiis line to read content (fortnightly)</option>
                                                            <option value="1-4">loremu test wright node care must thiis line to read content(weekly)</option>

                                                    </select>