Yea, thanks, I've read that. It doesn't cover selecting all the text in one gesture, which is what I want to be able to do. This doesn't seem to be covered.
I've been fooling around since I wrote the first post, and discovered that if you tap and hold to display the selection buttons (as noted in your quote) and then drag one of the blue selection buttons to the top (or bottom) of the text, then the other button will jump to the bottom (or top) and you have effectively selected all the text. This is what I wanted to do.
The reason I wanted to do it is so I can select all the text in an article that I want to read, then copy and paste it into an app I just got, Speak it!, and then have the app read me the article while I get some exercise riding my stationary bike.