Scrolling ad fixes for menus for larger amount of items overflowing due to new content

Due to having a lot more content the menu was being calculated with a top position of a negative value.
Also its height was lager than the client height. 

This is capped at 100% now and if it overflows then a vertical scrollbar is added.

An independent problem relating to menu positioning was also happening since the 8.1 upgrade since the onresize of divs wasn't being fired.