Flickable's mouse wheel scrolling keeps going inertially (past the location I want to scroll to)

[Daniel van Vugt]

Using a mouse wheel in Unity 8 > System Settings > Background works for scrolling. But it keeps scrolling inertially even after I've stopped rolling the wheel.

[For touchpad scrolling problems please see bug 1556795 instead, although both bugs may be fixed together]

[Daniel van Vugt (vanvugt)]

Hmm, maybe the problem is just QtMir speeding up/amplifying mouse wheel events a bit too much:

src/platforms/mirserver/qteventfeeder.cpp:

            const QPoint angleDelta = QPoint(hDelta * 15, vDelta * 15);
            mQtWindowSystem->handleWheelEvent(timestamp.count(), angleDelta, modifiers);

which then makes for a high scrolling velocity that takes a while to finish.

[Daniel van Vugt (vanvugt)]

Looks like the problem may get worse (even higher speed) when Ubuntu Touch gets Mir 0.21 or later with this fix:

https://code.launchpad.net/~andreas-pokorny/mir/fix-1539009-proper-accumulation-of-batched-events/+merge/286697

[Daniel van Vugt (vanvugt)]

Nope, Mir 0.22 on the phone didn't change this bug.

In other news, it appears the excessive inertial scrolling is app-specific. In the dash it scrolls to the top/bottom instantly on the slightest wheel movement. In System Settings however (main panel), wheel scrolling is better behaved and doesn't scroll anywhere near as far. Possibly still a bit too fast though.

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Daniel van Vugt (vanvugt)]

Erm, fixed for mouse wheels now (?!)

New issues with touchpad scrolling only, while I'll log separately.

[Daniel van Vugt (vanvugt)]

Sorry, still happening badly in the Apps scope. And only sometimes in the Background settings.

But see also new bug 1605513