Pushes an animatable region, so all further gtk_render_*() calls between
this call and the following Style.contextPopAnimatableRegion
will potentially show transition animations for this region if
Style.contextNotifyStateChange is called for a given state,
and the current theme/style defines transition animations for state
changes.
The region_id used must be unique in context so the themes
can uniquely identify rendered elements subject to a state transition.
Pushes an animatable region, so all further gtk_render_*() calls between this call and the following Style.contextPopAnimatableRegion will potentially show transition animations for this region if Style.contextNotifyStateChange is called for a given state, and the current theme/style defines transition animations for state changes.
The region_id used must be unique in context so the themes can uniquely identify rendered elements subject to a state transition.