IDLE: touchpad horizontal scrolling not working

[TheLizzard]

Bug report

Bug description:

I know that there isn't a horizontal scrollbar for a reason but I believe that horizontally scrolling on a touchpad/trackpad should still scroll the IDLE editor horizontally. Right now trying to horizontally scroll a file, scrolls it vertically which I find very counter intuitive. The reason for this behaviour is in Lib/idlelib/tree.py (which is used in Lib/idlelib/editor.py):

def wheel_event(event, widget=None):
    ...
    up = {EventType.MouseWheel: event.delta > 0,
          EventType.ButtonPress: event.num == 4}
    lines = -5 if up[event.type] else 5
    widget = event.widget if widget is None else widget
    widget.yview(SCROLL, lines, 'units')
    return 'break'

The function doesn't respect the direction of scrolling and instead just scrolls vertically (yview). I know this is a minor bug but it's annoying me so much when IDLE tries to scroll vertically when I am scrolling horizontally

CPython versions tested on:

CPython main branch

Operating systems tested on:

Linux, Windows

Linked PRs

• gh-140389: fixed touchpad horizontal scrolling in IDLE editor #140390