Implement #5 and #6

source/BonjourNode.swift

@@ -3,6 +3,7 @@ import Cocoa
 protocol BonjourNode:NSObjectProtocol {
 	var children:[Any] { get }
 	var objectValue:String { get }
+	var persistentName:String { get }
 	func start()
 	func stop()
 }

source/BrowserDelegate.swift

@@ -7,6 +7,7 @@ class BrowserDelegate:NSObject, NetServiceBrowserDelegate, BonjourNode {
 	// These need to be overridden
 	var children:[Any] { fatalError() }
 	var objectValue:String { fatalError() }
+	var persistentName:String { fatalError() }
 
 	func start() {
 		browser.includesPeerToPeer = true

source/BrowserWindowController.swift

@@ -1,6 +1,7 @@
 import Cocoa
 
 class BrowserWindowController:NSObject, NSOutlineViewDataSource, NSOutlineViewDelegate, NSWindowDelegate {
+	static let expandedUserDefaultsKey = "ExpandedItems"
 	let browserDelegate = RootBrowserDelegate()
 	let outlineView = CopyOutlineView()
 	let window:NSWindow = {
@@ -58,13 +59,29 @@ class BrowserWindowController:NSObject, NSOutlineViewDataSource, NSOutlineViewDe
 
 		scrollView.documentView = outlineView
 
+		outlineView.delegate = self
 		outlineView.dataSource = self // Do this last, because it causes data source methods to be called
 
 		NotificationCenter.default.addObserver(forName:.nodeDidAdd, object:nil, queue:nil, using:{
 			let object = $0.object
 			let parent = self.outlineView.parent(forItem:object)
 			self.outlineView.reloadItem(parent, reloadChildren:true)
-			self.outlineView.expandItem(object, expandChildren:true) // Auto-expand new items
+			if let node = object as? BonjourNode {
+				if let expandedDefaults = UserDefaults.standard.dictionary(forKey:BrowserWindowController.expandedUserDefaultsKey) {
+					let persistentName = node.persistentName
+					if let expandedNumber = expandedDefaults[persistentName] as? NSNumber {
+						if expandedNumber.boolValue {
+							self.outlineView.expandItem(node)
+						}
+						return
+					}
+				}
+
+				if node is DomainBrowserDelegate {
+					// Expand new domains
+					self.outlineView.expandItem(node)
+				}
+			}
 		})
 		NotificationCenter.default.addObserver(forName:.nodeDidRemove, object:nil, queue:nil, using:{
 			let object = $0.object
@@ -133,4 +150,58 @@ class BrowserWindowController:NSObject, NSOutlineViewDataSource, NSOutlineViewDe
 		}
 		return nil
 	}
+
+	func outlineViewItemWillExpand(_ notification:Notification) {
+		guard let userInfo = notification.userInfo else {
+			return
+		}
+		guard let object = userInfo["NSObject"] else {
+			return
+		}
+		guard let node = object as? BonjourNode else {
+			return
+		}
+
+		if node is ServiceDelegate {
+			node.start()
+		}
+
+		saveNode(node, expanded:true)
+	}
+
+	func outlineViewItemWillCollapse(_ notification:Notification) {
+		guard let userInfo = notification.userInfo else {
+			return
+		}
+		guard let object = userInfo["NSObject"] else {
+			return
+		}
+		guard let node = object as? BonjourNode else {
+			return
+		}
+
+		if node is ServiceDelegate {
+			node.stop()
+		}
+
+		saveNode(node, expanded:false)
+	}
+
+	func saveNode(_ node:BonjourNode, expanded:Bool) {
+		let standardUserDefaults = UserDefaults.standard
+		let key = BrowserWindowController.expandedUserDefaultsKey
+		let persistentName = node.persistentName
+		if var expandedDefaults = standardUserDefaults.dictionary(forKey:key) {
+			if let expandedNumber = expandedDefaults[persistentName] as? NSNumber {
+				if expandedNumber.boolValue == expanded {
+					return // No change in value
+				}
+			}
+			expandedDefaults[persistentName] = expanded
+			standardUserDefaults.set(expandedDefaults, forKey:key)
+		}
+		else {
+			standardUserDefaults.set([persistentName:expanded], forKey:key)
+		}
+	}
 }

source/DomainBrowserDelegate.swift

@@ -5,6 +5,7 @@ class DomainBrowserDelegate:BrowserDelegate {
 	var delegates = [ServiceBrowserDelegate]()
 	override var children:[Any] { return delegates }
 	override var objectValue:String { return domain }
+	override var persistentName:String { return domain }
 
 	required init(_ domain:String) {
 		self.domain = domain

source/ServiceBrowserDelegate.swift

@@ -6,6 +6,7 @@ class ServiceBrowserDelegate:BrowserDelegate {
 	var delegates = [ServiceDelegate]()
 	override var children:[Any] { return delegates }
 	override var objectValue:String { return type }
+	override var persistentName:String { return type + domain }
 
 	required init(type:String, domain:String) {
 		self.type = type
@@ -34,7 +35,6 @@ class ServiceBrowserDelegate:BrowserDelegate {
 		let newDelegate = ServiceDelegate(service)
 		delegates.append(newDelegate)
 		delegates.sort { $0.service.name < $1.service.name }
-		newDelegate.start()
 		NotificationCenter.default.post(name:.nodeDidAdd, object:newDelegate)
 	}
 

source/ServiceDelegate.swift

@@ -6,11 +6,13 @@ class ServiceDelegate:NSObject, NetServiceDelegate, BonjourNode {
 	var records = [String]()
 	var children:[Any] { return resolved + records  }
 	var objectValue:String { return service.name }
+	var persistentName:String
+	var started = false
 
 	required init(_ service:NetService) {
 		self.service = service
+		persistentName = "\(service.name).\(service.type)\(service.domain)"
 		super.init()
-		reloadTXTRecord()
 	}
 
 	@available(*, unavailable)
@@ -19,15 +21,22 @@ class ServiceDelegate:NSObject, NetServiceDelegate, BonjourNode {
 	}
 
 	func start() {
-		service.delegate = self
-		service.startMonitoring()
-		service.resolve(withTimeout:0.0)
+		if !started {
+			started = true
+			reloadTXTRecord()
+			service.delegate = self
+			service.startMonitoring()
+			service.resolve(withTimeout:0.0)
+		}
 	}
 
 	func stop() {
-		service.delegate = nil
-		service.stopMonitoring()
-		service.stop()
+		if started {
+			started = false
+			service.delegate = nil
+			service.stopMonitoring()
+			service.stop()
+		}
 	}
 
 	func netServiceDidResolveAddress(_ sender:NetService) {