We have for example a list of pages that can be configured to be shown in a menu.
We can create a multifield, but not with a pathbrowser.
We can create a pathbrowser, but it cannot be multi.
I think the current implementation of "multi" is not a correct one: multi should not be a separate configuration, but instead something that every configuration could be. I.e. a textfield could be multiple, a textarea could be multiple, a pathbrowser could be multiple, etc.
Back in April, when we implemented the pathbrowser widget, we ran into this issue and didn't find a good way to fix it yet, so maybe we can have a discussion here.