Can the size of the extension “window” be customizable (I have a pretty big screen at home and would like to capitalize on that).
At the moment, I have a few favorites and Identities and sometimes have to scroll to get to where I want.
That’s called a popup FYI 
Wouldn’t popup be when arrow icon is clicked and we get a new window?
Yes, I think the idea is that the extension drop-down should be customisable, rather than having to use the floating window. You could do this without additional menu options by giving the drop-down draggable sides & bottom that set the new size for future use, with the default size as a fixed minimum.
That’s the pop out window.