Some IDLE users really want a horizontal scrollbar (for the editor), and even consider its absence to be a reason to not use it.

Stackoverflow 2012: https://stackoverflow.com/questions/10301071/is-there-a-horizontal-scroll-bar-in-pythons-idle

Reddit 2020: https://stackoverflow.com/questions/10301071/is-there-a-horizontal-scroll-bar-in-pythons-idle
This was brought to my attention by Steven D'Aprano and specifically compare the IDLE editor to other editors.

I have decided to not wait until a possible major refactoring to add this feature.  The patch needs several revisions (see review).

I neglected to mention above (msg352888) that the scrollbar added to the font sample box is a Scrollbar subclass, textview.AutoHideScrollbar, that only appears when needed.  After experimenting with editing the font sample, I think we can just add this with no option to disable it.

Since editor windows already allow lines longer than the window width and already have horizontal scrolling by cursor motion, such as by Home, End, and Left and Right arrow keys, adding a horizontal scrollbar makes scrolling easier, but does not really change editor window behavior.  The disappearance of the scrollbar when a long line is sufficiently shortened makes it easier to determine when one has shortened a line enough to meet the window width as a limit, if one wishes. 

The shell is a different issue.  It wraps at the window width, just like standard interactive Python (as least on Windows with Command Prompt and macOS with Terminal).  I think something like the following is better wrapped.  If nothing else, copying to paste is easier ;-).  

>>> 2**1024
179769313486231590772930519078902473361797697894230657273430081157732675805500963132708477322407536021120113879871393357658789768814416622492847430639474124377767893424865485276302219601246094119453082952085005768838150682342462881473913110540827237163350510684586298239947245938479716304835356329624224137216

So, at least for now, no hbar for Shell.