I usually go for a combined approach: pre-type my long question in Notepad++, then post a polite "hello" immediately followed by another message with the actual

I usually go for a combined approach: pre-type my long question in Notepad++, then post a polite "hello" immediately followed by another message with the actual question. So it's both polite and considerate. It has a bonus point of not losing what you typed in case the chat window bugs out.