An animation may be scheduled while the textview content changed in size, so the resize
queued would just unset the animation and set the adjusments with a current value,
defeating gtk_text_view_scroll_to_iter(). In this case, just avoid the adjustment change,
as there is a target value on the way.
https://bugzilla.gnome.org/show_bug.cgi?id=733406
Add a private API that lets widget opt-in to animated updates of
the adjustment value. When enabled, all calls to
gtk_adjustment_set_value will smoothly transition from the old
value to the new value, using a fixed easing function and a
configurable duration. The animation is tied to the frame clock
of the widget.
By implementing this in GtkAdjustment, we can enable animation
for both scrollbars and keybindings, which are often implemented
in the child widget of the scrolled window.
https://bugzilla.gnome.org/show_bug.cgi?id=732376
