Sorry, it is not a case of backward compatibility, it is the fact that a set of open documents will then be opened in another version. This does not happen if I open v15, v12, v10 and earlier. v16 and v11 interfere with each other such that I cannot use them separately.
The code for "Hey! I've just opened, go and get all the files I left on the document tab bar and open them for me." "No, not the ones my buddy v16 has, mine!" is croak.
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