detachDragging property Null safety
Specifies whether user should not be able to scroll (drag) the panel after it is closed.
While user is dragging the panel to close it, and when it reaches to PanelSize.closedHeight, immediately the dragging is detached from the panel. Means, user can't re-open the panel by simply dragging.
NOTE that when you set this to true, a closed panel can ONLY be opened by a PanelController and will NOT handle user drags until opened. So, it is suggested to use when you are having PanelSize.closedHeight = 0.0. (This is not a restriction).
Default : false
final bool detachDragging;