and while here, make the explanation more explicit as to which values do
what, & use general Range terminology instead of focussing on scrollbars
https://bugzilla.gnome.org/show_bug.cgi?id=787669
/**
* GtkSettings:gtk-primary-button-warps-slider:
*
- * Whether a click in a #GtkRange trough should scroll to the click position or
- * scroll by a single page in the respective direction.
+ * If the value of this setting is %TRUE, clicking the primary button in a
+ * #GtkRange trough will move the slider, and hence set the range’s value, to
+ * the point that you clicked. If it is %FALSE, a primary click will cause the
+ * slider/value to move by the range’s page-size towards the point clicked.
+ *
+ * Whichever action you choose for the primary button, the other action will
+ * be available by clicking the middle mouse button (since GTK+ 3.22.25).
*
* Since: 3.6
*/