The DragIncrement property is only applicable when the TaskPositioning property is set to 'Proportional'.
The DragIncrement property can only be set when the Phase property returns 'Beginning'. Setting the property during any other phase will have no effect.
The DragIncrement property behaves exactly the same as the TaskDragIncrement property exposed by the control's TimelineSettings property. When the DragIncrement property is explicitly set, it overrides the value of the TimelineSettings property for that drag operation. When the property has not been set, the TimelineSettings level property is used, if it has been explicitly set. In the case where neither property is explicitly set, the effective drag increment is resolved based on the length of time spanned by the primary interval's time slots.
Target Platforms: Windows 10, Windows 8.1, Windows 8, Windows 7, Windows Server 2012, Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2