the prefix starts with underscores.

top of the window, unless it is too near the bottom to do do.

affected by a tk regression.  Initial patch by Mark Roseman.

now work on Mac Aqua.  Patch by Mark Roseman.

Start to split regrtest.py into smaller parts with the creation of
Lib/test/libregrtest/cmdline.py: code to handle the command line, especially
parsing command line arguments. This part of the code is tested by
test_regrtest.