You guys are missing the point - a spell checker won't flag a word like "effect" or "insure", when really what you mean is "affect" or "ensure".
Exactly. This is the problem of spell checker. For the guys who make some common mistakes, please notice-
Knew-NewKnew is past form of know and new is something which has been done for the first time.
Then-ThanThen means kind of times and than is used in comparison.
Their-There
Their is possessive form of they and there refers to a place actually.
Even-EventuallyEven generally refers to mention something specially. But eventually refers "in the end".
Doesn't the own forum correct misspellings?
OP is not talking about mispelling at all. Those are some common mistakes actually.
Doesn't the own forum correct misspellings? <...>
No, that is some feature related to your device/browser and textboxes.
It seems you are little wrong. There should be a feature in SMF which does correct the spelling as the guy said.