I am not sure when they added/"fixed" this, as Read Aloud wasn't previously available to the reading materials in the courses tool - you had to click the link to open the resource first, then Ctrl-R.
As I was going through a course this week, I accidentally hit Ctrl-R with no other pane open but the reading available in the course I was using (NT307 Archaeology and the New Testament) - and it started reading!
I was overjoyed! but it soon came to a halt, as i discovered that even though only the text for the reading was in the window (can't scroll before or after, the only text available to read is the section/part meant for that reading piece.) - the reader voice, kept on reading in the resource without stopping. 
so that's the bug - the reading aloud continues past what is actually seen in the courses tool.
