Changes the behaviour of scrolled_window with regard to the initial event that possibly starts kinetic scrolling. When capture_button_press is set to TRUE, the event is captured by the scrolled window, and then later replayed if it is meant to go to the child widget.
This should be enabled if any child widgets perform non-reversible actions on button-press-event. If they don't, and handle additionally handle grab-broken-event, it might be better to set capture_button_press to FALSE.
This setting only has an effect if kinetic scrolling is enabled.