feat: add support for preventing the system context menu (#25835)

Co-authored-by: Samuel Attard <[email protected]>

docs/api/browser-window.md

@@ -670,6 +670,20 @@ Emitted when the window has closed a sheet.
 
 Emitted when the native new tab button is clicked.
 
+#### Event: 'system-context-menu' _Windows_
+
+Returns:
+
+* `event` Event
+* `point` [Point](structures/point.md) - The screen coordinates the context menu was triggered at
+
+Emitted when the system context menu is triggered on the window, this is
+normally only triggered when the user right clicks on the non-client area
+of your window.  This is the window titlebar or any area you have declared
+as `-webkit-app-region: drag` in a frameless window.
+
+Calling `event.preventDefault()` will prevent the menu from being displayed.
+
 ### Static Methods
 
 The `BrowserWindow` class has the following static methods:

shell/browser/api/electron_api_base_window.cc

@@ -294,6 +294,12 @@ void BaseWindow::OnNewWindowForTab() {
   Emit("new-window-for-tab");
 }
 
+void BaseWindow::OnSystemContextMenu(int x, int y, bool* prevent_default) {
+  if (Emit("system-context-menu", gfx::Point(x, y))) {
+    *prevent_default = true;
+  }
+}
+
 #if defined(OS_WIN)
 void BaseWindow::OnWindowMessage(UINT message, WPARAM w_param, LPARAM l_param) {
   if (IsWindowMessageHooked(message)) {

shell/browser/api/electron_api_base_window.h

@@ -82,6 +82,7 @@ class BaseWindow : public gin_helper::TrackableObject<BaseWindow>,
   void OnTouchBarItemResult(const std::string& item_id,
                             const base::DictionaryValue& details) override;
   void OnNewWindowForTab() override;
+  void OnSystemContextMenu(int x, int y, bool* prevent_default) override;
 #if defined(OS_WIN)
   void OnWindowMessage(UINT message, WPARAM w_param, LPARAM l_param) override;
 #endif

shell/browser/native_window.cc

@@ -575,6 +575,13 @@ void NativeWindow::NotifyNewWindowForTab() {
     observer.OnNewWindowForTab();
 }
 
+void NativeWindow::NotifyWindowSystemContextMenu(int x,
+                                                 int y,
+                                                 bool* prevent_default) {
+  for (NativeWindowObserver& observer : observers_)
+    observer.OnSystemContextMenu(x, y, prevent_default);
+}
+
 #if defined(OS_WIN)
 void NativeWindow::NotifyWindowMessage(UINT message,
                                        WPARAM w_param,

shell/browser/native_window.h

@@ -287,6 +287,7 @@ class NativeWindow : public base::SupportsUserData,
   void NotifyTouchBarItemInteraction(const std::string& item_id,
                                      const base::DictionaryValue& details);
   void NotifyNewWindowForTab();
+  void NotifyWindowSystemContextMenu(int x, int y, bool* prevent_default);
 
 #if defined(OS_WIN)
   void NotifyWindowMessage(UINT message, WPARAM w_param, LPARAM l_param);

shell/browser/native_window_observer.h

@@ -92,6 +92,7 @@ class NativeWindowObserver : public base::CheckedObserver {
   virtual void OnTouchBarItemResult(const std::string& item_id,
                                     const base::DictionaryValue& details) {}
   virtual void OnNewWindowForTab() {}
+  virtual void OnSystemContextMenu(int x, int y, bool* prevent_default) {}
 
 // Called when window message received
 #if defined(OS_WIN)

shell/browser/native_window_views_win.cc

@@ -306,6 +306,12 @@ bool NativeWindowViews::PreHandleMSG(UINT message,
       }
       return false;
     }
+    case WM_CONTEXTMENU: {
+      bool prevent_default = false;
+      NotifyWindowSystemContextMenu(GET_X_LPARAM(l_param),
+                                    GET_Y_LPARAM(l_param), &prevent_default);
+      return prevent_default;
+    }
     default:
       return false;
   }