How to avoid NSTrackingSeparatorToolbarItem from overflowing when resizing a SplitView?

I am working on a macOS app and I am programmatically adding NSToolbarItems following Apple's documentation and I am adding the new NSTrackingSeparatorToolbarItem to support the new macOS 11 toolbar look and feel.

The tracking separator seems to work fine as long as I don't resize the split view below a certain width, then the separator breaks out and just looks out of place.

Is there a way to avoid this?? I don't want to hard code a minimum width, since the user might add items dynamically, and I just want to make sure that the split view does not force the tracking item to just pop out.

I could not find any code examples showing the new macOS 11 toolbar functionality.

On stack overflow I posted a question which shows 2 images with the described behavior.

thanks in advance
How to avoid NSTrackingSeparatorToolbarItem from overflowing when resizing a SplitView?
 
 
Q