For two periods last year, those using preview builds of Windows 10 could access to a feature called Sets: a tabbed interface that was eventually to allow tabs to be put in the titlebar of just about any window. These tabs would allow both multiple copies of the same application to be combined—a tabbed Explorer or Command Prompt, say—and multiple disparate windows to be grouped—combining, say, a browser window containing research with the Word window. However, both times the feature was enabled only for a few weeks, so Microsoft could gather data, before disabling it. Sets aren't in the Windows 10 May 2019 update.
The Shell-provided tab experience is no more, but adding tabs is high on our to do list.
— Rich Turner (@richturn_ms) April 20, 2019
It seems now that Sets are unlikely to ever materialize. Rich Turner, who oversees Microsoft's revamping of the Windows command-line infrastructure and the Windows Subsystem for Linux tweeted that the interface "is no more." Having everything tabbed everywhere isn't going to happen. Adding tabs specifically for command-line windows is, however, "high on [Microsoft's] to do list."
There was initially some confusion that the tweet might have meant that some other system-wide approach to tabs was going to be used. But Turner clarified today that the command-line tabs will be purpose-built for command-line windows, not a general feature for the entire operating system.