http://www.smartclient.com/smartgwt/showcase/#tree_miller_columns
If you click the link above;you can see Column Tree sample… If you use left click on the first column member ‘Charles Madigen’ open second column and you can see second column members… up untill now everything like seem correctly… But if you use rigth click on the second column member you willl see third column and it’s member but you will see a pop up menu before Column Tree…(first time not seem anythink please try this different member).