Test a non-BMP Unicode character (a.k.a. emoji) in both 
file text and name:

	A non-BMP emoji => 😊

This file can be opened in PyEdit with a File->Open (and, on
Mac, with Finder's drag-and-drops, Open Withs, and clicks).

It doesn't break the GUI or later open dialogs (thanks to both
Tk and tkinter-bug workarounds), but the emoji is replaced 
with the Unicode replacement character (the diamond question
mark) for display in both file name and file content, and
is replaced permanently in file content saved to files (alas, 
full-scale emoji silliness must await a future Tk...).

The upside is that Unicode symbols in the U+0000..U+FFFF 
BMP (UCS-2) code-point range work fine in Tk and PyEdit:

	BMP Unicode symbols => ✓ ☓ ☑ ☒ ☀ ☼ ☉ ★ ☆ ☞ ☜