可折叠面板和下拉菜单的动态定位

I'm developing a code which needs to dynamically position a drop down menu which is inserted under a collapsible panel. The problem is when the panel get collapsed you need to scroll vertically in order to come to the drop down, drop down get lost and opens outside of the windows. But when the collapsible is closed everything works fine. What is the JQuery positioning code which always accurately opens drop down under the button in different screen sizes and different scroll bar positions? here is the sample code I developed:I'm developing a code which needs to dynamicall