No, there is no shell. Only main() function can be evaluated. You may be interested in http://tryerlang.org/, but it is much more restricted.
I don't understand about which window you are talking about. May you make a screenshot?
I think he might be referring to the 80 column vertical line
Re:Try Erlang online
by quarterwave on Wednesday February 11, 2015 @10:24PM
(#9037199)
That's correct, thanks for pointing it out.
There seems to be a sub-window to the right of the module editor, but I'm unable to place the cursor there.
Tried in both Firefox 35 and Chrome 39.