1-Something common to other apps which would really be useful (and a time saver) when mulitiple drawings are open, is to have in the Windows menu a "Save All" and "Close All files".
2-From the File > Open menu, allow the user to select multiple files and open them all as separate drawings. Also, From the File > Import menu, allow the user to select mulitiple files and open them all into the same drawing.
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