[FIX] CSS: When using Chosen, dropdown menus at the bottom of "panels" (e.g. tracker field options) would be cut off making the menu unusable. This fix makes ugly scrollbars appear when you select the menu, but at least functionality is restored. CSS file changed manually as i still can't compile LESS

git-svn-id: file:///var/local/code.tiki.org/tikisvn/branches/13.x@52912 b456876b-0849-0410-b77d-98878d47e9d5