Obtains the frame clock for a widget.
The frame clock is a global “ticker” that can be used to drive animations and repaints. The most common reason to get the frame clock is to call get_frame_time, in order to get a time to use for animating. For example you might record the start of the animation with an initial value from get_frame_time, and then update the animation by calling get_frame_time again during each repaint.
request_phase will result in a new frame on the clock, but won’t necessarily repaint any widgets. To repaint a widget, you have to use queue_draw which invalidates the widget (thus scheduling it to receive a draw on the next frame). queue_draw will also end up requesting a frame on the appropriate frame clock.
A widget’s frame clock will not change while the widget is mapped. Reparenting a widget (which implies a temporary unmap) can change the widget’s frame clock.
Unrealized widgets do not have a frame clock.
a FrameClock, or null if widget is unrealized