Steps to reproduce

1. Create a group in the users page
2. Open admin page
3. Scroll down to "Exclude groups from sharing"
4. Tick checkbox
5. Open dropdown

Expected result

Dropdown opens

Actual result

Dropdown does not open.

Versions

Works in OC 7.0.2 but broken on stable7.

I've bisected this and it comes down to this commit from @jancborchardt 30cc4b9

It is very strange how a simple overflow can mess up multiselect.

I'll try and find a compatible solution for multiselect.