Lateral mouse movement stops scroll wheel

[René J.V. Bertin]

On Wednesday July 29 2020 22:31:31 Russell Haley wrote:

>Hi, I'll try to catch all the previous emails here. The DE is Mate and no
>other applications exhibit the issue.
Aren't you contradicting this with
>I haven't checked any other qt or KDE applications so
>I'll do that asap.

Supposing KDevelop is indeed the only affected application (and Kate isn't, in particular) it just might be related to the considerable amount of "event hooks" KDevelop exploits for adding its own content in the editor views. Context menus are built on the fly each time you call them up for instance, using an "about to show" signal relayed from Qt through the KTextEditor framework.
In addition to testing with a large text document that has no meaning for KDevelop (check the possible effect of spell checking too!) you could try with a non-editor view in KDevelop that can be scrolled (in both directions). The file (not project!) manager sidebar widget might be good for that.

FWIW, I mentioned weird quirks I get with context menus on Mac (only with the native "cocoa" QPA, not the xcb QPA!) and I think those are due to all those event hook processing taking long enough for other events to come in and mess things up. Think menus that close, open unexpectedly, need an additional click to open or jump around on my screen, all things that don't happen if I use keyboard shortcuts ... or when I open a context menu in the sidebar. Your symptoms are different but if really KDevelop is the only app showing them then it does seem they must be related.
(Incidentally, this is the main reason I figured out how to patch Qt so it supports the Menu key on my external keyboard...)