Menu dropdowns don't work in footers

[cheekygit]

Menu dropdowns will expand towards the bottom even if the parent menu item is already at the bottom of the page. It seems there should be a way to adjust this behavior but I cannot find it in the documentation of pure menus.

[redonkulus]

The new menus in 0.6.0 are CSS only, you will need to add JS to support this functionality.

#424