onDragStart property
A callback when the user starts to move the thumb.
This will be called only once when the drag begins. This provides you with the ThumbDragDetails.
This method is useful if you are planning to do something like add a time label and/or video preview over the thumb and you need to do some initialization.
Use onSeek if you only want to seek to a new audio position when the drag event has finished.
Implementation
final ThumbDragStartCallback? onDragStart;