We are having some difficulty figuring out how to properly manage the ActiveRow appearnce when the user uses ctrl-click to select and deselect rows. The active-row is always visually highlighted eventhough it is no longer part of the Selected:Rows collection.
I'll be back on Monday 18-01.
Have a look at this kb.
http://devcenter.infragistics.com/Support/KnowledgeBaseArticle.aspx?ArticleID=10117