For How do I draw a plot with a variable line width in pgfplots?, after answers and comments started coming in, I realised that I really want a continuous change in line width, and not a discrete one as I answered to a comment in the beginning. This is a detail in the question, but might result in a quite different answer. Which of the following alternatives is right?
Should I change the question slightly, so that the already given answer no longer answers the question?
Should I ask a new question, even if it is very similar to the existing question?
IMHO it would be best to leave the original question as it is/was and add an edit, explaining that you were actually looking for something slightly different. This does not invalidate the previous answer(s) and keeps the issue general enough if someone is looking it up, so the user can readily choose from several answers, without having to look up several entries. This also reduces the risk of duplicates in the future (in case a user doesn't find all questions related to his own problem).