Re the side panel, you're probably thinking of "Drawers".
Here's a screenshot https://www.oreilly.com/api/v2/epubs/0596003706/files/tagore...
> Oh also the + button didn't do full screen as today, but... it did... something. I never understood the point of the + button.
When I first came from Windows I was confused about this as well, but once I got the hang of it, it became the most logical thing to me.
The green + button zoomed the window to the minimum window size that showed the full content. (For example, one page in a word processor or one slide in presentation software.)
It's called "maximize". You can get the + back by pressing Option while clicking the green circle.
Double clicking the title bar in many applications will also maximize the window.
Oh also the + button didn't do full screen as today, but... it did... something. I never understood the point of the + button.