 	var rootVariables:[Variable] = []
 	var changedIndexes:Set<Int> = []
 	var variablePopover:NSPopover?
+	var isVisible = false
 	@IBOutlet var varTableView:NSTableView?
 	
 	override func viewWillAppear() {

		if sessionOptional != nil {
			session.startWatchingVariables()
		}
	}
	
	override func viewWillDisappear() {

	}
	
	override func sessionChanged() {
		if isVisible {
			session.startWatchingVariables()
		}
	}
	
	func variableNamed(name:String?) -> Variable? {
