While testing the Site Editor, we noticed that the fullscreen mode's WP icon usage isn't immediately clear.
The icon is used to either close the editor and navigate back to the dashboard (in the Post Editor), or to open the Navigation sidebar (in the Site Editor).
In the Post Editor it might be slightly clearer: the WP icon could subtly hint that it's a link back to the WP dashboard.
Although, when a site icon is set, that subtle hint ceases to exist.
Neither a WP icon nor a site icon are semantically connected to either "close" or "menu" meanings, which are more commonly referred to with the "X" (or "back arrow") and "hamburger" icons respectively.
While testing the Site Editor, we noticed that the fullscreen mode's WP icon usage isn't immediately clear.
The icon is used to either close the editor and navigate back to the dashboard (in the Post Editor), or to open the Navigation sidebar (in the Site Editor).
In the Post Editor it might be slightly clearer: the WP icon could subtly hint that it's a link back to the WP dashboard.
Although, when a site icon is set, that subtle hint ceases to exist.
Neither a WP icon nor a site icon are semantically connected to either "close" or "menu" meanings, which are more commonly referred to with the "X" (or "back arrow") and "hamburger" icons respectively.