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 Frame.clockGetFrameTime, 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 Frame.clockGetFrameTime, and then update the animation by calling Frame.clockGetFrameTime again during each repaint.
Frame.clockRequestPhase will result in a new frame on the clock, but won’t necessarily repaint any widgets. To repaint a widget, you have to use Widget.queueDraw which invalidates the widget (thus scheduling it to receive a draw on the next frame). Widget.queueDraw 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.