+ 6.1 (Jan 27, 2018)
+ Interface changes:
+
+ + X/Open Curses specifies a "reserved" void* parameter in several
+ functions, saying that it must be NULL. In this release, if the
+ parameter is non-NULL, it is interpreted as a point to an integer
+ containing a color pair. In previous releases, a non-NULL parameter
+ caused an error return. Portable applications are unaffected. Here
+ are the functions which have been extended:
+ attr_get
+ attr_off
+ attr_on
+ attr_set
+ chgat
+ color_set
+ mvchgat
+ mvwchgat
+ slk_attr_off
+ slk_attr_on
+ slk_attr_set
+ wattr_get
+ wattr_on
+ wattr_off
+ wattr_set
+ wchgat
+ wcolor_set
+
+ + the TERMINAL structure declared in <term.h> has been made opaque,
+ and its size increased to handle the increased size of color pair
+ and color value, as well as other numeric capabilities.
+
+ A few applications required change, e.g., to use def_prog_mode;
+ only one application (tack) is known to have a valid reason for
+ accessing these internal details, and that was addressed by the
+ release of tack 1.08 in 2017. Internal functions marked as used
+ by tack will be deprecated in future releases.
+
+ Added extensions:
+
+ + Several new functions were added to manipulate extended color pairs
+ and color values. These include:
+ alloc_pair
+ extended_color_content
+ extended_pair_content
+ extended_slk_color
+ find_pair
+ free_pair
+ init_extended_color
+ init_extended_pair
+ reset_color_pairs
+
+ as well as corresponding sp-functions.
+
+ + A new terminfo capability "RGB" tells the ncurses library that the
+ color values are red/green/blue, to eliminate the need for palettes
+ in that special case for the color_content function.
+
+ Added internal functions (other than "_sp" variants):
+ _nc_copy_termtype2
+ _nc_export_termtype2
+ _nc_fallback2
+ _nc_find_prescr
+ _nc_forget_prescr
+ _nc_free_termtype2
+ _nc_read_entry2
+ _nc_write_object
+
+ Removed internal functions:
+ _nc_check_termtype
+ _nc_resolve_uses
+
+ Modified internal functions:
+
+ + symbols are used by tic/infocmp/toe:
+ _nc_align_termtype - change parameters to TERMTYPE2*
+ _nc_check_termtype2 - change parameter to TERMTYPE2*
+ _nc_read_file_entry - change parameter to TERMTYPE2*
+ _nc_read_termtype - change parameter to TERMTYPE2*
+ _nc_trim_sgr0 - change parameter to TERMTYPE2*
+ _nc_write_entry - change parameter to TERMTYPE2*
+
+ + symbols used only within the library:
+ _nc_fallback - change return type to TERMTYPE2*
+ _nc_init_termtype - change parameter to TERMTYPE2*
+