Useful it will be, the 'tree buttons', near favorite and history buttons, for open or close tree panels. Buttons must have 2 positions: on/off.
This visual layout show clearly the new TC 7 improvement, witch is very easy to use in this way!
Even, mouse context menu must have option to open/close tree panel for each file panel, somewhere in path or files panel.
Remember:

I know the menu options and I know how to put those command on the default bar.
But is not the subject of the topic.
Best wishes,