PageTree toolbar not fixed when included in tab

[RadLikeWhoa]

I've just discovered a bug where the toolbar of the PageTree is not displayed correctly.

Steps to reproduce:

1. Enable FlatNav
2. Add a preset of type tree
3. Scroll down the page tree

The toolbar (plus button etc.) scrolls along with the content instead of being fixed to the top of the tab.

The issue is easily resolved by setting the tab panel and it's first to div descendants to height: 100% and the page tree container to display: flex; flex-direction: column;.

Problem is, I'm not sure if this is an issue with FlatNav or the UI in general so I have no idea where I could fix this.

[dimaip]

Hey Sacha, thanks for reporting!
You could try to override the styles from inside this package, but if those styles make sense as a default, a fix would be welcome in the neos-ui package itself.