over child widgets that also react to scrolling
like GtkComboBox, GtkScale and GtkSpinButton,
because otherwise when you're in the middle of
scrolling the view/window you can involuntarily
scroll over the widgets and change its values.
This problem can be seen in applications like
pavucontrol, gnome-tweaks prefs, devhelp prefs,
and so on.
Fixes issue #3092