Rac. Control
Parent class for controls that use an anchor object to determine the
visual position of the control's interactive elements.
A control mantains a current value within the range
[startValue,endValue], which by default is set to [0,1].
Additionally a control can be configured with markers to highlight
the positions of certain values, and with a specific `style`` to use when
drawing.
⚠️ The API for controls is planned to change in a future minor release. ⚠️