Basically, when I make edits to a file, very often the Undo button icon in the toolbar doesn't change to show that the action is undoable. Clicking it also will not undo an action. I have found that clicking the tab will then update the undo status and the icon changes and is then active, allowing undo actions to take place.
It's not a major issue, just a little annoying really. So if there's other more important stuff to fix, maybe leave this for now?
