如何关闭（X）关闭按钮点击事件的对话框？

My mobile website has some multiselect controls. The multiselect that have a little number of items (5) appears normally, like a multiselect (in mobile style/format), but those that have more items than 5 appears like an dialog view, in a new page. For some reason, the X button is unresponsive and doesn't have the colse effect. What should I do to make the X button works? multiselect code:My mobile website has some multiselect controls