You were already answered. It is appropriate for the MDI client to be scrolled if that is the user's intention.
It is inappropriate if it is not the user's intention, but this is not mIRC's fault.
Rather than blindly disagreeing or ignoring responses, why not suggest what mIRC should do to fix this. Is it your opinion that mIRC should completly disable scrolling the MDI client window? If so, that will never happen, since your "fix" will be breaking the ability for others to do exactly that: scroll the MDI client window.
