I’ve been getting to know Simple:Press. I became a Silver Member just yesterday. What has surprised me the most is that there seems to be no option for threaded or nested discussions. I was surprised by that. I’m still a little surprised considering how many other features Simple:Press does have.
As I’m writing this, I’m also realizing that Simple:Press does not have spell checking.
I do like it though. 
I would suggest you search our forum for discussion on threaded topics or nested topics… not sure what is different as each topic is a thread.. is it just indentation?
but of course, always open to new ideas and suggestions…
as to spell checking, not sure what you mean… FF, Chrome, IE and other major browsers all do spell checking on textarea inputs for post content… they underline misspelled words in red… its why wp removed the spell checker from the wp editor (what we use for posting if using tinymce plugin)… can you elaborate further? does your browser not make spelling suggestions automatically?
Hum, you’re right about the spelling. Seems like most of the forums I’ve used always had spell check button.
But on the nesting, it might not be absolute necessary, but it is a nice way to know who is talking to who. If five people reply to a topic, and someone wants to comment on one of those replies, the nesting makes it easier to keep up with who is replying to who.
thanks for confirming the spell checker…
out of curiosity, did you search here for some of the other topics… just to see some of the previous discussion…
since a topic is well, related to the topic, everyone in the topic is talking to each other… if someone goes off topic, seems like that post should be moved to a new topic… keep topics on topic… 
but that may just be me… we have had a couple of other requests for nested posts (vice topics) within a topic…
that said, I have noted your request too…