diff --git a/NetNewsWire/MainWindow/Detail/DetailViewController.swift b/NetNewsWire/MainWindow/Detail/DetailViewController.swift
index c00f58b5f..e3b0d1e4c 100644
--- a/NetNewsWire/MainWindow/Detail/DetailViewController.swift
+++ b/NetNewsWire/MainWindow/Detail/DetailViewController.swift
@@ -49,7 +49,7 @@ final class DetailViewController: NSViewController, WKUIDelegate {
 	// MARK: - API
 
 	func setState(_ state: DetailState, mode: TimelineSourceMode) {
-		// TODO: also to-do is caller
+		webViewController(for: mode).state = state
 	}
 
 	func canScrollDown(_ callback: @escaping (Bool) -> Void) {
@@ -65,14 +65,17 @@ final class DetailViewController: NSViewController, WKUIDelegate {
 
 extension DetailViewController: DetailWebViewControllerDelegate {
 
-	func mouseDidEnter(_ link: String) {
-		guard !link.isEmpty else {
+	func mouseDidEnter(_ detailWebViewController: DetailWebViewController, link: String) {
+		guard !link.isEmpty, detailWebViewController === currentWebViewController else {
 			return
 		}
 		statusBarView.mouseoverLink = link
 	}
 
-	func mouseDidExit(_ link: String) {
+	func mouseDidExit(_ detailWebViewController: DetailWebViewController, link: String) {
+		guard detailWebViewController === currentWebViewController else {
+			return
+		}
 		statusBarView.mouseoverLink = nil
 	}
 }
@@ -87,4 +90,13 @@ private extension DetailViewController {
 		controller.state = .noSelection
 		return controller
 	}
+
+	func webViewController(for mode: TimelineSourceMode) -> DetailWebViewController {
+		switch mode {
+		case .regular:
+			return regularWebViewController
+		case .search:
+			return searchWebViewController
+		}
+	}
 }
diff --git a/NetNewsWire/MainWindow/Detail/DetailWebViewController.swift b/NetNewsWire/MainWindow/Detail/DetailWebViewController.swift
index df77cfafa..85b167c23 100644
--- a/NetNewsWire/MainWindow/Detail/DetailWebViewController.swift
+++ b/NetNewsWire/MainWindow/Detail/DetailWebViewController.swift
@@ -12,8 +12,8 @@ import RSWeb
 import Articles
 
 protocol DetailWebViewControllerDelegate: class {
-	func mouseDidEnter(_ link: String)
-	func mouseDidExit(_ link: String)
+	func mouseDidEnter(_: DetailWebViewController, link: String)
+	func mouseDidExit(_: DetailWebViewController, link: String)
 }
 
 final class DetailWebViewController: NSViewController, WKUIDelegate {
@@ -85,10 +85,10 @@ extension DetailWebViewController: WKScriptMessageHandler {
 
 	func userContentController(_ userContentController: WKUserContentController, didReceive message: WKScriptMessage) {
 		if message.name == MessageName.mouseDidEnter, let link = message.body as? String {
-			delegate?.mouseDidEnter(link)
+			delegate?.mouseDidEnter(self, link: link)
 		}
 		else if message.name == MessageName.mouseDidExit, let link = message.body as? String{
-			delegate?.mouseDidExit(link)
+			delegate?.mouseDidExit(self, link: link)
 		}
 	}
 }
diff --git a/NetNewsWire/MainWindow/MainWindowController.swift b/NetNewsWire/MainWindow/MainWindowController.swift
index e4817fc36..1402c8779 100644
--- a/NetNewsWire/MainWindow/MainWindowController.swift
+++ b/NetNewsWire/MainWindow/MainWindowController.swift
@@ -70,6 +70,7 @@ class MainWindowController : NSWindowController, NSUserInterfaceValidations {
 		sidebarViewController.delegate = self
 
 		timelineContainerViewController = splitViewController?.splitViewItems[1].viewController as? TimelineContainerViewController
+		timelineContainerViewController.delegate = self
 
 		NotificationCenter.default.addObserver(self, selector: #selector(applicationWillTerminate(_:)), name: NSApplication.willTerminateNotification, object: nil)
 
@@ -369,7 +370,7 @@ class MainWindowController : NSWindowController, NSUserInterfaceValidations {
 
 extension MainWindowController: SidebarDelegate {
 
-	func sidebarSelectionDidChange(to selectedObjects: [AnyObject]?) {
+	func sidebarSelectionDidChange(_: SidebarViewController, selectedObjects: [AnyObject]?) {
 		// TODO: if searching, cancel search
 		timelineContainerViewController.setRepresentedObjects(selectedObjects, mode: .regular)
 		timelineContainerViewController.showTimeline(.regular)
@@ -378,6 +379,22 @@ extension MainWindowController: SidebarDelegate {
 	}
 }
 
+// MARK: - TimelineContainerViewControllerDelegate
+
+extension MainWindowController: TimelineContainerViewControllerDelegate {
+
+	func timelineSelectionDidChange(_: TimelineContainerViewController, articles: [Article]?, mode: TimelineSourceMode) {
+		let detailState: DetailState
+		if let articles = articles {
+			detailState = articles.count == 1 ? .article(articles.first!) : .multipleSelection
+		}
+		else {
+			detailState = .noSelection
+		}
+		detailViewController?.setState(detailState, mode: mode)
+	}
+}
+
 // MARK: - Scripting Access
 
 /*
diff --git a/NetNewsWire/MainWindow/Sidebar/SidebarViewController.swift b/NetNewsWire/MainWindow/Sidebar/SidebarViewController.swift
index a1e5f8a07..88a337465 100644
--- a/NetNewsWire/MainWindow/Sidebar/SidebarViewController.swift
+++ b/NetNewsWire/MainWindow/Sidebar/SidebarViewController.swift
@@ -13,7 +13,7 @@ import Account
 import RSCore
 
 protocol SidebarDelegate: class {
-	func sidebarSelectionDidChange(to: [AnyObject]?)
+	func sidebarSelectionDidChange(_: SidebarViewController, selectedObjects: [AnyObject]?)
 }
 
 @objc class SidebarViewController: NSViewController, NSOutlineViewDelegate, NSOutlineViewDataSource, NSMenuDelegate, UndoableCommandRunner {
@@ -385,7 +385,7 @@ private extension SidebarViewController {
 	}
 
 	func selectionDidChange(_ selectedObjects: [AnyObject]?) {
-		delegate?.sidebarSelectionDidChange(to: selectedObjects)
+		delegate?.sidebarSelectionDidChange(self, selectedObjects: selectedObjects)
 	}
 
 	func updateUnreadCounts(for objects: [AnyObject]) {
diff --git a/NetNewsWire/MainWindow/Timeline/TimelineContainerViewController.swift b/NetNewsWire/MainWindow/Timeline/TimelineContainerViewController.swift
index 79b0942dc..30527642b 100644
--- a/NetNewsWire/MainWindow/Timeline/TimelineContainerViewController.swift
+++ b/NetNewsWire/MainWindow/Timeline/TimelineContainerViewController.swift
@@ -6,12 +6,19 @@
 //  Copyright © 2019 Ranchero Software. All rights reserved.
 //
 
-import Cocoa
+import AppKit
+import Articles
+
+protocol TimelineContainerViewControllerDelegate: class {
+	func timelineSelectionDidChange(_: TimelineContainerViewController, articles: [Article]?, mode: TimelineSourceMode)
+}
 
 final class TimelineContainerViewController: NSViewController {
 
 	@IBOutlet var containerView: TimelineContainerView!
-	
+
+	weak var delegate: TimelineContainerViewControllerDelegate?
+
 	private lazy var regularTimelineViewController = {
 		return TimelineViewController(delegate: self)
 	}()
@@ -38,8 +45,8 @@ final class TimelineContainerViewController: NSViewController {
 
 extension TimelineContainerViewController: TimelineDelegate {
 
-	func selectionDidChange(in: TimelineViewController) {
-		// TODO: notify MainWindowController
+	func timelineSelectionDidChange(_ timelineViewController: TimelineViewController, selectedArticles: [Article]?) {
+		delegate?.timelineSelectionDidChange(self, articles: selectedArticles, mode: mode(for: timelineViewController))
 	}
 }
 
@@ -53,4 +60,15 @@ private extension TimelineContainerViewController {
 			return searchTimelineViewController
 		}
 	}
+
+	func mode(for timelineViewController: TimelineViewController) -> TimelineSourceMode {
+		if timelineViewController === regularTimelineViewController {
+			return .regular
+		}
+		else if timelineViewController === searchTimelineViewController {
+			return .search
+		}
+		assertionFailure("Expected timelineViewController to match either regular or search timelineViewController, but it doesn’t.")
+		return .regular // Should never get here.
+	}
 }
diff --git a/NetNewsWire/MainWindow/Timeline/TimelineViewController.swift b/NetNewsWire/MainWindow/Timeline/TimelineViewController.swift
index a3ca815d0..4d277a7fc 100644
--- a/NetNewsWire/MainWindow/Timeline/TimelineViewController.swift
+++ b/NetNewsWire/MainWindow/Timeline/TimelineViewController.swift
@@ -12,7 +12,7 @@ import Articles
 import Account
 
 protocol TimelineDelegate: class  {
-	func selectionDidChange(in: TimelineViewController)
+	func timelineSelectionDidChange(_: TimelineViewController, selectedArticles: [Article]?)
 }
 
 final class TimelineViewController: NSViewController, UndoableCommandRunner {