anchor.diff:    final SnapPosition initSnapPosition;
   
     /// If true, the grabbing widget can not be draget below the lowest [snapPositions]
  -  /// or over the heightest [snapPositions].
  +  /// or over the highest [snapPositions].
     final bool lockOverflowDrag;
   
     /// The controller for the [SnappingSheet]
  
positive.code:         this.minHeight = null,
          this.maxHeight = null;
  
    /// Make the sheet height fit the avaiable space
    const SnappingSheetHeight.fit()
        : this._type = SnappingSheetType.fit,
          this.expandOnSnapPositionOverflow = false,
  
negative.code:   }
  }
  
  /// Controls the [SnappingSheet] widget
  class SnappingSheetController {
    Function(SnapPosition value) _setSnapSheetPositionListener;
  
  