fix: child window alwaysOnTop level persistence (#29956)

shell/browser/api/electron_api_base_window.cc

@@ -867,6 +867,10 @@ void BaseWindow::SetVibrancy(v8::Isolate* isolate, v8::Local<v8::Value> value) {
 }
 
 #if defined(OS_MAC)
+std::string BaseWindow::GetAlwaysOnTopLevel() {
+  return window_->GetAlwaysOnTopLevel();
+}
+
 void BaseWindow::SetWindowButtonVisibility(bool visible) {
   window_->SetWindowButtonVisibility(visible);
 }
@@ -1253,6 +1257,7 @@ void BaseWindow::BuildPrototype(v8::Isolate* isolate,
       .SetMethod("isVisibleOnAllWorkspaces",
                  &BaseWindow::IsVisibleOnAllWorkspaces)
 #if defined(OS_MAC)
+      .SetMethod("_getAlwaysOnTopLevel", &BaseWindow::GetAlwaysOnTopLevel)
       .SetMethod("setAutoHideCursor", &BaseWindow::SetAutoHideCursor)
 #endif
       .SetMethod("setVibrancy", &BaseWindow::SetVibrancy)

shell/browser/api/electron_api_base_window.h

@@ -191,6 +191,7 @@ class BaseWindow : public gin_helper::TrackableObject<BaseWindow>,
   virtual void SetVibrancy(v8::Isolate* isolate, v8::Local<v8::Value> value);
 
 #if defined(OS_MAC)
+  std::string GetAlwaysOnTopLevel();
   void SetWindowButtonVisibility(bool visible);
   bool GetWindowButtonVisibility() const;
   void SetTrafficLightPosition(const gfx::Point& position);

shell/browser/native_window.h

@@ -201,6 +201,7 @@ class NativeWindow : public base::SupportsUserData,
 
   // Traffic Light API
 #if defined(OS_MAC)
+  virtual std::string GetAlwaysOnTopLevel() = 0;
   virtual void SetWindowButtonVisibility(bool visible) = 0;
   virtual bool GetWindowButtonVisibility() const = 0;
   virtual void SetTrafficLightPosition(base::Optional<gfx::Point> position) = 0;

shell/browser/native_window_mac.h

@@ -79,6 +79,7 @@ class NativeWindowMac : public NativeWindow,
   void SetAlwaysOnTop(ui::ZOrderLevel z_order,
                       const std::string& level,
                       int relative_level) override;
+  std::string GetAlwaysOnTopLevel() override;
   ui::ZOrderLevel GetZOrderLevel() override;
   void Center() override;
   void Invalidate() override;

shell/browser/native_window_mac.mm

@@ -875,6 +875,31 @@ void NativeWindowMac::SetAlwaysOnTop(ui::ZOrderLevel z_order,
   SetWindowLevel(level + relative_level);
 }
 
+std::string NativeWindowMac::GetAlwaysOnTopLevel() {
+  std::string level_name = "normal";
+
+  int level = [window_ level];
+  if (level == NSFloatingWindowLevel) {
+    level_name = "floating";
+  } else if (level == NSTornOffMenuWindowLevel) {
+    level_name = "torn-off-menu";
+  } else if (level == NSModalPanelWindowLevel) {
+    level_name = "modal-panel";
+  } else if (level == NSMainMenuWindowLevel) {
+    level_name = "main-menu";
+  } else if (level == NSStatusWindowLevel) {
+    level_name = "status";
+  } else if (level == NSPopUpMenuWindowLevel) {
+    level_name = "pop-up-menu";
+  } else if (level == NSScreenSaverWindowLevel) {
+    level_name = "screen-saver";
+  } else if (level == NSDockWindowLevel) {
+    level_name = "dock";
+  }
+
+  return level_name;
+}
+
 void NativeWindowMac::SetWindowLevel(int unbounded_level) {
   int level = std::min(
       std::max(unbounded_level, CGWindowLevelForKey(kCGMinimumWindowLevelKey)),
@@ -1803,10 +1828,15 @@ void NativeWindowMac::InternalSetParentWindow(NativeWindow* parent,
 
   // Set new parent window.
   // Note that this method will force the window to become visible.
-  if (parent && attach)
+  if (parent && attach) {
+    // Attaching a window as a child window resets its window level, so
+    // save and restore it afterwards.
+    NSInteger level = window_.level;
     [parent->GetNativeWindow().GetNativeNSWindow()
         addChildWindow:window_
                ordered:NSWindowAbove];
+    [window_ setLevel:level];
+  }
 }
 
 void NativeWindowMac::SetForwardMouseMessages(bool forward) {

spec-main/api-browser-window-spec.ts

@@ -1418,15 +1418,12 @@ describe('BrowserWindow module', () => {
   describe('BrowserWindow.setAlwaysOnTop(flag, level)', () => {
     let w = null as unknown as BrowserWindow;
 
+    afterEach(closeAllWindows);
+
     beforeEach(() => {
       w = new BrowserWindow({ show: true });
     });
 
-    afterEach(async () => {
-      await closeWindow(w);
-      w = null as unknown as BrowserWindow;
-    });
-
     it('sets the window as always on top', () => {
       expect(w.isAlwaysOnTop()).to.be.false('is alwaysOnTop');
       w.setAlwaysOnTop(true, 'screen-saver');
@@ -1454,6 +1451,16 @@ describe('BrowserWindow module', () => {
       const [, alwaysOnTop] = await alwaysOnTopChanged;
       expect(alwaysOnTop).to.be.true('is not alwaysOnTop');
     });
+
+    ifit(process.platform === 'darwin')('honors the alwaysOnTop level of a child window', () => {
+      w = new BrowserWindow({ show: false });
+      const c = new BrowserWindow({ parent: w });
+      c.setAlwaysOnTop(true, 'screen-saver');
+
+      expect(w.isAlwaysOnTop()).to.be.false();
+      expect(c.isAlwaysOnTop()).to.be.true('child is not always on top');
+      expect((c as any)._getAlwaysOnTopLevel()).to.equal('screen-saver');
+    });
   });
 
   describe('preconnect feature', () => {