This is not really that important but I'm recording it for posterity.

If you open a directory in TM2 so that you have a window showing the file browser and an empty "untitled" document, then click on a file in the browser that is not UTF-8 encoded you will get the dialog asking for which encoding to use.   If you click "cancel" in that dialog the entire window is closed.  Unlike when you close the last tab  and you get a new "untitled" document.