Mouse scroll jumps

P_Aleksandrov

Sometimes mouse wheel scrolling works wrong: when I, for example, click on a menu and then try to scroll - scrolling jumps. It seems that this bug was reported, but it is marked as closed: https://bugreports.qt.io/browse/QTBUG-38274. I have tried Qt 5.7.0 (KDE Neon), 5.7.1 (from Ubuntu Zesty) and Qt 5.8.0 from qt.io (installer): this error appears in all versions. The bug appears, for example, with LyX 2.2.2 during scrolling the document. I use Ubuntu 16.10 amd64 with Xorg, Logitech G300s mouse. This bug doesn't appear while using Qt4 and GTK applications.
How can I corrent this error?

SGaist

Hi and welcome to devnet,

Do you mean provide a patch for it or have a workaround ?

If the later, the current last post on the bug report gives a possible hint.

P_Aleksandrov

This bug appears in applications which are not written by me. I don't have a patch or workaround. It seems that this bug is something like https://bugreports.qt.io/browse/QTBUG-49294. But at the least in LyX jumping doesn't always happen after opening and closing context menu. And jumping takes place after switching to and from another application or clicking by left mouse button on toolbars. Similar behaviour take place in another Qt5 apps.

SGaist

One thing you can to is test if it still happening with 5.8.0.

Otherwise, you can try taking a look at what is happening with QWheelEvent::angleDelta() .

devel

I can reproduce it with Logitech G300 mouse. But there is no problem with a different Logitech mouse.

Looks like some additional input events confuse Qt.

SGaist

Can you check the difference of input events between your other mouse and the Logitech G300 ?

devel

It's no secret. This mouse acts like keyboard and mouse to do its gaming features.

There is a similar report: https://bugs.freedesktop.org/show_bug.cgi?id=97510

Workaround is:

Section "InputClass"
    Identifier "Ignore keyboard mouse device"
    MatchIsKeyboard "on"
    MatchProduct "Logitech Gaming Mouse G300"
    Option "Ignore" "on"
EndSection

But it kills a half of the mouse.

SGaist

Thanks for that very interesting link.

Kamajii

Just FYI, to me this very issue happens also when I connect a Logitech Unifying Device wireless dongle to my computer (it came with my trackball), although it only reports itself as a pointer in xinput.