Byungin,
To the best of my knowledge, the feature that you describe is not available in LV 6i. However, some alternatives that might be satisfactory for your application are the
Tab Control (under FP >> Array & Cluster) and VI Server (BD >> Application Control). Tab Control is pretty self explanatory once you look at it; VI Server is a way to programatically control features and functionality of VIs (e.g. programatically making a front panel appear and disappear). You can find out more about VI Server by visiting
http://zone.ni.com/devzone/devzoneweb.nsf/opendoc?openagent&89FB741908D9808886256990006EB88E&cat=2E4161187E3DEB30862568660020BCC8
HTH,
Rich