Cannot change file extension in the title bar

[velotiger]

Environment

• CotEditor: 4.0.1 (455)
• System: macOS Version 11.0.1 (Build 20B50)
• Language: German

Short Description

It is no longer possible to remove or change a file extension in the
editor's title bar.

Steps to Reproduce the Issue

I have file «New Document.txt» in the editor (e.g. output of a script
received by CotEditor's script mechanism «NewDocument»). I want to
rename this file to «mydoc.yaml», «mycode.py» or whatever. The
editor accepty the new name, but insists on appending «.txt» to the
entire file name. Result is «mydoc.yaml.txt», «mycode.py.txt», …
This seems rather absurd because it is perfectly possible to rename
the file in the finder as intended and CotEditor silently (that's good)
updates the file's in its title bar.

In Versions prior to 4.x, it was possible to change a file's extension
if the file has not been saved before. Once a file has been saved, the
behaviour of CotEditor 3.x was as described above fpr CotEditor 4.0.1.

Expected Result

It is possible to change or remove a file's extension in the editor's
title bar. More clearly: It is possible to change the entire name of
the file, that means basename and file extension.

[KrishnaMBhattarai]

I have the same issue. I will start another ticket for this

[1024jp]

Sorry I missed reacting to this issue. Under the latest modern macOS, it seems impossible to change them from the titlebar. There are a lot of tricky things around file type handling due to Apple's Sandboxing mechanism. But well, I'll study it again later.

@Qrishna Thank you for the other report. But please continue the discussion here instead of making multiple tickets for a single issue. I'll close the new one for duplication.

[1024jp]

Short update: During the WWDC 2022, I asked about this issue to an engineer in Apple. According to his answer, it seems there is no way to change this behavior straightforwardly.