This could very well be end-users favorite new LEX feature, giving them the ability to customize their own nav bars. First, open up what you'd like to see on the nav bar, this could be a dashboard, report, list view, etc. and then choose Open in New Tab. Use the drop...

Release Notes: https://releasenotes.docs.salesforce.com/en-us/spring18/release-notes/salesforce_release_notes.htm Pre-Release Org: https://www.salesforce.com/form/signup/prerelease-spring18.jsp