the steady event from slider now moved here. A spec test suite and the
corresponding implementations will follow.
This needs to be reworded, there's no "slider" now, but "widget".
Called when the widget's value has changed and has remained unchanged for 0.2s. This allows filtering out unwanted "noise" from the widget if you are only interested in its final position. Use this event instead of @[Efl.Ui.Range_Display.changed] if you are going to perform a costly operation on its handler.