fix: show maximized frameless window (#30804)

shell/browser/native_window_views.cc

@@ -1629,8 +1629,17 @@ void NativeWindowViews::OnMouseEvent(ui::MouseEvent* event) {
 }
 
 ui::WindowShowState NativeWindowViews::GetRestoredState() {
-  if (IsMaximized())
+  if (IsMaximized()) {
+#if defined(OS_WIN)
+    // Only restore Maximized state when window is NOT transparent style
+    if (!transparent()) {
+      return ui::SHOW_STATE_MAXIMIZED;
+    }
+#else
     return ui::SHOW_STATE_MAXIMIZED;
+#endif
+  }
+
   if (IsFullscreen())
     return ui::SHOW_STATE_FULLSCREEN;
 

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

@@ -4647,4 +4647,32 @@ describe('BrowserWindow module', () => {
       });
     });
   });
+
+  describe('"transparent" option', () => {
+    afterEach(closeAllWindows);
+
+    // Only applicable on Windows where transparent windows can't be maximized.
+    ifit(process.platform === 'win32')('can show maximized frameless window', async () => {
+      const display = screen.getPrimaryDisplay();
+
+      const w = new BrowserWindow({
+        ...display.bounds,
+        frame: false,
+        transparent: true,
+        show: true
+      });
+
+      w.loadURL('about:blank');
+      await emittedOnce(w, 'ready-to-show');
+
+      expect(w.isMaximized()).to.be.true();
+
+      // Fails when the transparent HWND is in an invalid maximized state.
+      expect(w.getBounds()).to.deep.equal(display.workArea);
+
+      const newBounds = { width: 256, height: 256, x: 0, y: 0 };
+      w.setBounds(newBounds);
+      expect(w.getBounds()).to.deep.equal(newBounds);
+    });
+  });
 });