RE: Infragistics silverlight control objects - grid control
As far as I understand, you mean Infragistics NetAdvantage for Silverlight Data Visualization 2009 Volume 2. Currently, TestComplete does not provide special support for these controls. However, you can try working with these controls by using the general approach to working with Silverlight applications that is described in the "Testing Silverlight Applications with TestComplete" article.
BTW, you can vote for your controls on the following web page: