Feature request: Give a hint if some option need restart to take effect

[xaljer]

I found that "keep file close" seems need restart to take effect. If some options do need restart, it's better to give a hint to user.

[variar]

Yes, that's inconvinient. However, that should work when file is closed and reopened. Some "follow" options also work that way. It would be better to find a way of applying them on-the-fly.

[xaljer]

Maybe we can done this by two steps: first, give a description around the option, and then try to apply them on-the-fly.