Adds two Duration values together.
Assembly: System.Windows (in System.Windows.dll)
Return ValueType: System.Windows.Duration
If both Duration values have TimeSpan values, this method returns the sum of those two values. If either value is set to Automatic, the method returns Automatic. If either value is set to Forever, the method returns Forever.
If either t1 or t2 has no value, this method returns null.
For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.