+ 6.5 (TBD; not stable; in development)
+ Interface changes:
+
+ + the WINDOW structure and some related internal data types declared
+ in <curses.h> have been made opaque by default;
+ + the FORM, MENU, and PANEL structures and related internal data types
+ from their corresponding header files have been made opqaue by
+ default; and
+ + support for wide characters is now enabled by default.
+
+ 6.4 (Dec 31, 2022)
+ Interface changes:
+
+ + none
+
+ Added extensions:
+
+ + none
+
+ Added internal functions (other than "_sp" variants):
+
+ + add _nc_free_termtype1 and _nc_free_tparm, for memory-leaks
+
+ Removed internal functions:
+
+ + none
+
+ Modified internal functions:
+
+ + none
+