I've noticed that there is no way to limit the number of total files open at once. There is an explorer.openEditors.visible option, but that seems to limit the height of the "Open Editors" pane (which I don't use - I use tabs instead).

To keep my workspace focused, I like my editor to automatically close files over a set threshold that I have least recently viewed. Obviously, it wouldn't close files that have unsaved changes (or it would prompt you prior to trying to close them).

Does this sound like a reasonable request? Please let me know!