Scrolling and resize fixes

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. 

Resizing fixes for 8.1 (which were also broken in 8.0 app on 8.1 but in a different way)