While editing 'IDLE-console differences' (added in the patch above) for #35099, I decided that it should be renamed (to, say, 'Executing user code') and limited to the effect of executing user code in IDLE's execution process instead of a standard python process. Except for a intentional change to make developing tkinter code easier, such effects are unintended and possibly bad for developers using IDLE.

This issue is about one aspect of how IDLE's Shell, in the GUI process, displays strings and bytes sent from the execution process via sys.stdout and sys.stderr.  My previous revision of the title was wrong and my previous patch not directly relevant.

I will make a new patch to add a new section ('Displaying user code output'?) describing various aspects of how Shell displays std text output, starting with this one.  Most of the differences from various consoles and terminal are intentional and considered to be net positives.

While the handling of control characters is inherited from tk, Serhiy and I have claimed on other issues that displaying one glyph per character has advantages for development as well as disadvantages.  (Being about to display all but only the BMP subset of unicode is also inherited from tcl/tk.)

One of my unposted ideas is to add an option to the run menu to run edited code in the system console/terminal, detached from IDLE, the same as if the file were run from a command line or directory listing.  This would bypass both IDLE's execution and display effects.