It would be nice to use the whole window for the Plex view during read-only browsing the Brain.
In a big brain, having more space for the Plex window is crucial. And when you are just browsing, you do not really need the Tool box window.
Unfortunately, you have to show the Tool box if you want to see the Note text.
So, my suggestion is to show the Note text on the Plex window, when the mouse moves over to the Note indication Icon, which is on the right hand side. Show the Note text the same way as the images are shown on the left hand side.
With that feature you could use the whole program window for the Plex window.
It would be greatly enhance the presentation mode as well. It would be more obvious which Thought the Note text belongs to.