macos/Runner/MainFlutterWindow.swift

@@ -5,6 +5,11 @@ import desktop_multi_window
 class MainFlutterWindow: NSWindow {
   override func awakeFromNib() {
     let flutterViewController = FlutterViewController()
+    // Keep hover events flowing while this window is not key (e.g. when a
+    // dialog or the beamer window is in front): otherwise an element that was
+    // hovered when the window lost key status keeps its hover styling because
+    // the matching exit event is never delivered.
+    flutterViewController.mouseTrackingMode = .inActiveApp
     let windowFrame = self.frame
     self.contentViewController = flutterViewController
     self.setFrame(windowFrame, display: true)

third_party/desktop_multi_window/macos/Classes/FlutterMultiWindowPlugin.swift

@@ -107,6 +107,12 @@ class MultiWindowManager: NSObject {
         let project = FlutterDartProject()
         project.dartEntrypointArguments = ["multi_window", windowId, config.arguments]
         let flutterViewController = FlutterViewController(project: project)
+        // By default Flutter only delivers hover (mouse-moved) events to the
+        // key window. The audience/beamer window is borderless and never
+        // becomes key (the keyboard must stay with the presenter), so without
+        // this it would never see hover at all — and state set by a click
+        // (e.g. a chart highlight) would never be cleared again.
+        flutterViewController.mouseTrackingMode = .inActiveApp
         window.contentViewController = flutterViewController
         window.setFrame(NSRect(x: 0, y: 0, width: 800, height: 600), display: true)