The default property value. If no previous property exists, or the
preferences store is unavailable, this value will be returned.
returnType
The return type. This must be a type
supported by the System.Convert class. The supported types are:
Boolean, Char, SByte, Byte, Int16, Int32, Int64, UInt16, UInt32,
UInt64, Single, Double, Decimal, DateTime and String.
Return Value
Returns the property value (with the same type as returnType).