Flex setting the selectedItem on a tree freezes the application

application start freezing, after I debugged the code I found that the problem was the Tree setter selectedItem, googling I found this page http://forums.adobe.com/thread/823041 with people that have the same issue, the solution suggested was to call validateProperties before the problematic setter, this worked to make the app not freeze but the selectedItem did not done it's job so I used a callLater function to set the selectedItem  after an interval