public virtual unowned Alpha begin_animation (uint duration, ulong mode)
Warning: begin_animation is deprecated since 1.12.
Begins an animation of
duration milliseconds, using the provided easing
The result of this function depends on the this implementation
the duration of the animation, in milliseconds
the easing mode of the animation
The Alpha created by the layout manager; the returned instance is owned by the layout manager and should not be unreferenced