ncurses does not include BUTTON5_* constants

[msjyoo]

BPO	39273
Nosy	@serhiy-storchaka, @NoSuck, @ZackerySpytz, @msjyoo
PRs	bpo-39273: Expose BUTTON5_* constants in the curses module if available #17996

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = None
closed_at = <Date 2021-01-14.09:40:58.297>
created_at = <Date 2020-01-09.06:59:01.409>
labels = ['library', '3.10', 'type-crash']
title = 'ncurses does not include BUTTON5_* constants'
updated_at = <Date 2021-01-14.09:40:58.295>
user = 'https://github.com/msjyoo'

bugs.python.org fields:

activity = <Date 2021-01-14.09:40:58.295>
actor = 'serhiy.storchaka'
assignee = 'none'
closed = True
closed_date = <Date 2021-01-14.09:40:58.297>
closer = 'serhiy.storchaka'
components = ['Library (Lib)']
creation = <Date 2020-01-09.06:59:01.409>
creator = 'michael.yoo@akunacapital.com'
dependencies = []
files = []
hgrepos = []
issue_num = 39273
keywords = ['patch']
message_count = 3.0
messages = ['359657', '378252', '385065']
nosy_count = 4.0
nosy_names = ['serhiy.storchaka', 'IronGrid', 'ZackerySpytz', 'michael.yoo@akunacapital.com']
pr_nums = ['17996']
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'crash'
url = 'https://bugs.python.org/issue39273'
versions = ['Python 3.10']

[msjyoo]

Hi,

Recently I was working with ncurses, and when handling the mouse scroll events, I noticed that the curses library does not include the BUTTON5_* macros provided by ncurses. On my system, BUTTON5 corresponds to the mouse down event.

Is there a reason for this, or has it just not been updated? If so, the expectation is that it exists.

Relevant source location: https://github.com/python/cpython/blob/2bc3434/Modules/_cursesmodule.c#L4668

[NoSuck]

This baffled me, as well. Does the reason involve bit-field width?

By the way, look at what my Python installation does when just pressing button 5 (mouse wheel down) after calling curses.mousemask():

_curses.error: getmouse() returned ERR

The curses program then crashes with an exit code of 1.

$ uname -srvmo
Linux 5.4.51-v7l+ python/cpython#45674 SMP Mon Aug 10 16:51:40 BST 2020 armv7l GNU/Linux
$ python3 -V
Python 3.7.3