Nested SubMenu's are hidden if the ul has y-scrolling

[joshkarges]

How To Reproduce

Try the storybook demo: https://kontentino.github.io/react-multilevel-dropdown/?path=/story/dropdown--default

Open up the dev tools console, and set this style on the ul element:

    max-height: 90px;
    overflow-y: auto;

Now when you try to open up the subMenu, it's hidden.

I haven't found a good way to solve this. This comes close, but relies on very fragile CSS and updating the position of the subMenu regularly: https://css-tricks.com/popping-hidden-overflow/