IDLE: Run ... Customized strips backslashes from arguments

PART 1/2

Actions
In editor, do "Run... Customized"
In text box, Paste or type a valid Windows path (e.g.: c:\Users, \\server\share)
Select "OK"

Expected response:
script receives argument as entered without modification just as it does when run on the command line (e.g.: python prog.py c:\users)

Actual response:
script receives argument with backslashes treated as escape characters (e.g.: c:users, \servershare)

Workaround:
argument is not altered if entered in quotes. This is not the same behavior as the command line where quotes are accepted as part of the argument.

Part 2/2

Actions
In editor, do "Run... Customized"

Expected response:
text box is populated with previous entry, a legal windows path (e.g. `c:\Users)

Actual response:
text box is populated with previous entry mangled as above surrounded by curly braces (e.g.: {c:users}, {\serverpath}). If workaround above is used, then the string is correct, but quotes are gone and curly braces are present (e.g.: {c:\users}, {\\server\share}

System information

Windows 10 Home x86-64 (21H1 build 19043.1706)
Idle version 3.10.4

Linked PRs

• gh-157635

Start with IDLE's Run... Customized workflow and reproduce the Windows path cases described in the issue, including the saved-entry behavior. Review linked PR gh-157635 before making changes; done means arguments retain their backslashes and the customized-entry field preserves the entered path as expected.