Asks the frame clock to run a particular phase.
The signal corresponding the requested phase will be emitted the next time the frame clock processes. Multiple calls to request_phase will be combined together and only one frame processed. If you are displaying animated content and want to continually request the gdk_frame_clock_phase_update phase for a period of time, you should use [ method@Gdk.FrameClock.begin_updating] instead, since this allows GTK to adjust system parameters to get maximally smooth animations.
the phase that is requested