Select elements with long titles from relationship boxes break out of meta box

I noticed recently that any select elements in relationship meta boxes containing extra long post titles in them push out beyond the meta box container (when the metabox is located in the sidebar to the right). See screenshot.

This seems to be fixed by applying max-width:100%; to:

.rwmb-field .select2-container {}
in meta-box/css/select-advanced.css

Here's a screenshot after applying the fix.