DX-Site-Root: ZMI Nav-Tree is no longer expandable

[agitator]

After migrating to dx-site-root, the navtree within the zmi is no longer expandable

#2454 @jaroel @ale-rt

[ale-rt]

I will have a look!

[petschki]

This is true for all dexterity.Container classes ... would be cool if the containers could expand in ZMI in general ...

[jensens]

What a rabbit hole! Wanna feel like Alice? Go here https://github.com/zopefoundation/Zope/blob/master/src/App/dtml/menu.dtml and here https://github.com/zopefoundation/DocumentTemplate/blob/master/src/TreeDisplay/TreeTag.py
Need more mushrooms or tea....

[jaroel]

Before you enable this by default, please keep in mind that BTreeFolder2 objects may contain many many many items ;)

[jensens]

For the site root we want it expandable. I doubt anyone adds there N-many items. And if: IDK