The difference from before is that the settings are now on the
Highlights tab instead of the Extensions tab and only change one theme
at a time instead of all themes. The default for light themes is black
on light gray, as before. The default for the IDLE Dark theme is white
on dark gray, which better fits the dark theme.
When one starts IDLE from a console and loads a custom theme without
definitions for 'context', one will see a warning message on the console.
To stop the warning, go to Options => Configure IDLE => Highlights,
select the custom theme if not selected already, select 'Code Context',
and select foreground and background colors.
Instead of displaying a fixed number of lines, some blank, Code Context
now displays the variable number of actual context lines. When there
are no context lines, it shows a single blank line to indicate that the
feature is turned on.
The Code Context configuration option is changed from 'numlines'
(default 3) to 'maxlines' (default 15) to avoid possible interference
between user settings for the old and new versions of Code Context.
