Mouse Scroll Action Buffered Instead of Triggered

With commit 3bc0f172 [1], scrolling window content triggers only on the second and subsequent steps.

If only one step is scrolled before moving the cursor again, the scrolling still does not trigger on the first step. The action instead seems to be 'buffered' as many times as the cursor movement and scrolling only one step is repeated, and once finally getting to two steps on the same cursor position, all of the 'buffered' steps will be triggered at once.

Tested on Gentoo Linux, using KWin (5.12.6), LXQt (git master), Falkon (git master), KWrite (18.04.3), and qTox (git master) to name a few applications.

1. http://code.qt.io/cgit/qt/qtbase.git/commit/?id=3bc0f1724ae49c2fd7e6d7bcb650350d20d12246