Tab Remains on File Close

Version 2.0.0 nightly revision 63fe67a, Windows 7.

After closing a .mscz file (via menu, Ctrl-F4 or X), its tab (only) remains in the workspace. See attached.

Interestingly, the tab disappears when MuseScore loses focus.

This is probably trivial, unless indicative of some deeper issue (eg, file not fully closed and expunged from workspace). It is, however, a bit disconcerting!