"Maximizing Tor Browser" Notification can exist multiple times

The following Message that overlays the top part of the browser when maximizing it, can open itself multiple times. See i.imgur.com/hQfxjO1.png

Steps to reproduce:

  1. Open Tor (6.0.3)
  2. Maximize (message shows up)
  3. Revert to other size then maximum / minimum
  4. Repeat 2,3

Multiple messages now lie on top of each other which have to be closed individually.

Expected behavior: Only one of those messages can be open at one time.

Trac:
Username: oldmanjohnson

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