The Minimize button 
minimizes Instant Text. While
linked, you can
also use the Alt+- shortcut
to
minimize Instant Text: this shortcut acts as
a
toggle and using it a second time restores Instant Text.
The
"Restore" button 
switches Instant Text to the the Built-in Editor Layout. You can
also use the Alt+/ keyboard shortcut to toggle between the Client Layout and the Built-in Editor Layout.
The Close button 
closes Instant Text.