Pushes an animatable region, so all further gtk_render_*() calls between
this call and the following gtk_style_context_pop_animatable_region()
will potentially show transition animations for this region if
gtk_style_context_notify_state_change() 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 gtk_style_context_pop_animatable_region() will potentially show transition animations for this region if gtk_style_context_notify_state_change() 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.