This is a rebase of @websurfer5's #13534 against master, since that PR no longer applies cleanly and has not been updated since May. It now appears to pass the check that was failing in #13534 (review).

The original description from @websurfer5's PR follows.

ncurses 6.1 adds extended color functions to support terminals with 256 colors (e.g. xterm-256color). The extended functions use color-pair values that are signed integers because the existing functions only use signed short integer values that are too small to support the 65,536 color-pair values needed for a 256-color terminal.

The new extended color functions are used transparently by curses.color_content(), curses.init_color(), curses.init_pair(), and curses.pair_content() when available, and the original functions are used when they aren't. The module functions validate their parameters as signed integers when using the new extended functions and as signed short integers when using the original library functions to match the underlying ncurses function parameters. The original behavior remains unchanged when Python is built with a curses library that does not contain the new extended color functions.

A new function, curses.has_extended_color_support(), indicates whether extended color support is provided by the underlying ncurses library.

This PR also fixes issue #36630.

• Issue: Add support for extended color functions in ncurses 6.1 #81163