General Update: We have done 1, 3, 7, 8, 9, 11, 17, 21.  Very nice.  A re-organized list of the remainder (with old numbers).

Docs:
D1: idle.rst subsection on Code Context (19, see #33642).
D2: What's New in 3.6.6 and 3.7.0 (20).

Menu
M1: put Code Context and Zoom Height on same menu (5).
M2: Add Show/Hide Code Context (5).
M3. Gray out menu entry when not applicable (6).
M3: Shortcut for CC? (new),

Code Context Display
C1. Add vertical scrollbar if lines > maxlines (12).
C2. Add horizontal scrollbar if add to text (13).

Internal Changes
I1. Unspecified code cleanups for codecontext.py (2)
I2. Reduce events (4). Font change notification (15). Text active or text changed notification (16).

External Changes
E1. Mark blocks in editor (10, unlikely).
E2. Navigate by blocks in editor (14).
E3. Error check maxlines in configdialog (18).

D1 is PR 7579 and backports.  D2 was done on #33820 and #33821.

For M1, I would still like to move Zoom Height to Options with a separate bar after IDLE settings.