Turning a feature on or off is not a problem to me. I've learned to use mIRC's options to suit my needs, to shape this client to the way I like it. However, for many others, an insignifiant change has a very strong impact; see the last paragraph in my first reply on this thread. That is my whole point: how many people would appreciate the new feature and try to learn to benefit from it, versus how many people will delete the new mIRC and keep the old one because it is simpler to delete than reading the documentation.
The spell checker could eventually become like the agent support; most users don't even know it's there, but the few who really find it useful will appreciate it exists. I am only concerned that, a) implementing this feature will take a lot of time and might not be justified by the number of users who will take advangate of it, and b) if things are not implemented properly (as in, the spell checker to be disabled by default), people will find it difficult to adapt to the new version.
Off-topic question: is it possible to add a spell checker in the form of an agent?
From what I've seen, most people are not going to learn anything on IRC, and especially will disregard their own typing. "What is this, English class? Get a life. It's IRC!" - I've been told more than once. People are so lazy that they will type "thx" instead of "thanks", thinking that saving 3 keystrokes has the excuse that everybody is using it. Allow me to be pessimistic about the success of the spell checker.
By the way, another thing I hate, apart from chopped words and nonsense sentences, is when others abuse the Quote function of the forum, to disect a message in tiny pieces taken out of context, then argue against them one by one.
Remember, this is simply a collection of opinions regarding a development suggestion, not an argument to prove the others wrong. If you want to be helpful, move on from "you can turn it off" answer which has been repeated too many times; find arguments to support your ideas. In the end, it's up to Khaled if he implements the spell checker or not; we're here to help him find the best way to approach this feature suggestion.
I have to agree that improvements to the scripting language shouldn't take that much of a priority; latest versions mostly fixed identifiers and other script-related bugs. I'd like to see other changes as well, features available to the user without the need of a script. This thread is not the place to enumerate them.