Closing FX window shouldn't be a state in undo history (DONE)

[Casualty]

If I open an fx chain window on a track, it doesn't get entered as a separate state in undo history, but if I close the same window it does (close fx chain config).

This causes problems when you go back and forth in history. If doing so causes an fx chain window to become closed, then that state gets entered into undo history and all other entries beyond that point are permanently lost.

I've brought this up a couple of times before - it'd be great if "Close FX Chain Config" was not a state in undo history.

I believe Dandruff was with me on this when I brought it up before....