Lihui: >From your sub-vi, you can =93Set Control Value=94 of a Boolean =93hidebutton=94 (just for the lack of better names) in main.vi to true using vi property node. (Or you can also write to a global variable that can be accessed in main.vi) In the main.vi, you can wire it to a case structure (or better yet to a dynamics events structure in LabVIEW 7.0), which has the property node/visible set to false inside it. When Boolean hide button is set to true, you will be able to hide the button. You could set visible to true in when boolean "hidebutton" is false as well if it's convinient for you
I hope this helps, FightOnSCTrojan