Fix for random scrolling when using hierarchical data

When using hierarchical data there is a random scroll jump when hovering over select options. The reason is that in the case of hierarchical data the highlightable choices are <ul> and thus their outer height is many pixels (includes the children's height as well). A fix is to make the height calculations by using the the label divs.
Merge pull request #1095 from nolamesa/patch-1

Fix for random scrolling when using hierarchical data