Extra title rendered on macOS

[jackplus-xyz]

When creating a new tab in fullscreen mode, an extra title is rendered on the left hand side of the title bar.

• It doesn't seem to be related to the tabs count.
• It happens when creating or closing a tab

The minimal config to recreate this issue:

title = "Hello" 
macos-titlebar-style = tabs

[mitchellh]

I think this is #1945.