Expansion Field (ManipulationDelta)
The change in distance between touch contacts, as DIPs. For example, if the distance between two contacts changes from 100 DIPs to 200 DIPs during a manipulation, the value of Expansion would be 100.0.
Target Platforms: 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