The TaskDragIncrement property is only applicable when the TaskPositioning property is set to 'Proportional'.
The TaskDragIncrement property controls the "sensitivity" of mouse movement during a drag operation. Since task drag operations cause time-related values to change, the property's type is System.TimeSpan. Setting the property to a smaller value causes the TaskElementDragging event to fire more frequently, with smaller changes in time intervals with each firing.
Because the value of the ColumnWidth property determines the amount of time spanned by a pixel, the effect of the TaskDragIncrement property is dependent on the value of the ColumnWidth property.
For example, consider a PrimaryInterval of one hour with the ColumnWidth property set to 60; this causes each pixel on the screen to represent one minute. If TaskDragIncrement is set to a time span of five minutes, the mouse pointer must move five pixels in order to register as a movement during a drag operation. Such a movement will cause the value of the applicable Task property to change by exactly five minutes. With a value of 120 for the ColumnWidth property in the same scenario, the user would have to move the mouse pointer by 10 pixels in order to change the value by the same 5 minutes.
The TaskDragIncrement property applies to the time-related drag operations for tasks, which coincide with the constants defined by the TaskDragType enumeration.
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