According to
issue 1324 the Use External Editor option has been discontinued because it conflicts/is made redundant by the added command-line support.
This doesn't make immediate sense to me. Before it was as simple as checking a box in Prefs. Now... ? Can someone run through what this change actually means and how I can go back to using an external editor? The documentation unfortunately has not been keeping up ver well with the changes to 2.0.