...the dot means that you've posted something in that thread.... if you started it, you'll see the dot or if you post something in someone else's thread, you'll also see the dot.... hope that this clears up your question....
Here is another question. My previous post was edited about 10 seconds after I submitted it - saw that Taoist already answered it ahead of me - why doesnt it list it as being edited?
...i've often wondered the same thing.... seems like if you go back and edit it quick enough, it doesn't show up.... but if you wait a couple of minutes, it will show as "edited" ...excellent query.