Comment 98 for bug 1228250

I know it's not qt, but qt has this notion of QWheelEvent::DefaultDeltasPerStep – maybe gtk has that too?

Anyway, I recently implemented a fix for a problem in the linux KDE application gwenview, where, when you used CTRL+Touchpad_scroll to zoom in/out, it was horribly sensitive (see here for bug/patch https://bugs.kde.org/show_bug.cgi?id=378584#c7). For the fix we would always accumulate deltas upon triggered events and only perform the action once the accumulated delta is greater than or equal to QWheelEvent::DefaultDeltasPerStep (at the same time resetting the accumulated delta to 0).

Using the scroll wheel, the emitted delta is exactly QWheelEvent::DefaultDeltasPerStep, such that the action is performed at each turn of the wheel.