fix(macos): stop mouse clicks from being dropped after a cursor warp

src/platform/macos/macos_backend.cpp

@@ -484,14 +484,28 @@ namespace lvh::detail {
 
     /**
      * @brief Shared macOS backend state.
+     *
+     * Local-event suppression on `source` is set to zero so cursor warps do not
+     * discard the following click or mouse-moved events. CoreGraphics copies
+     * that configuration into each event at creation time, so `mouse_event` is
+     * refreshed from `source` after the interval is configured.
      */
     class MacosInputState {
     public:
       MacosInputState():
           source {CGEventSourceCreate(kCGEventSourceStateHIDSystemState)},
           keyboard_source {CGEventSourceCreate(kCGEventSourceStatePrivate)},
           mouse_event {source ? CGEventCreate(source) : nullptr},
-          scroll_lines_per_detent_value {read_scroll_lines_per_detent(scrollwheel_scaling)} {}
+          scroll_lines_per_detent_value {read_scroll_lines_per_detent(scrollwheel_scaling)} {
+        // Each move warps the cursor. The default 250ms suppression then drops the
+        // following click and mouse-moved events. The cursor image still moves.
+        if (source) {
+          CGEventSourceSetLocalEventsSuppressionInterval(source, 0);
+          if (mouse_event) {
+            CGEventSetSource(mouse_event, source);
+          }
+        }
+      }
 
       MacosInputState(const MacosInputState &) = delete;
       MacosInputState &operator=(const MacosInputState &) = delete;
@@ -510,9 +524,9 @@ namespace lvh::detail {
         }
       }
 
-      CGEventSourceRef source {};  ///< CoreGraphics event source for mouse and scroll events.
+      CGEventSourceRef source {};  ///< Mouse/scroll source with local-event suppression disabled.
       CGEventSourceRef keyboard_source {};  ///< CoreGraphics event source for keyboard events.
-      CGEventRef mouse_event {};  ///< Reusable CoreGraphics mouse event.
+      CGEventRef mouse_event {};  ///< Reusable mouse event refreshed from `source` after suppression is disabled.
       double scrollwheel_scaling = default_scrollwheel_scaling;  ///< Raw macOS scroll-wheel scaling preference.
       int scroll_lines_per_detent_value = default_scroll_lines_per_detent;  ///< Logical lines per wheel detent.
       CGEventFlags keyboard_flags {};  ///< Active modifier flags applied to mouse events.

tests/fixtures/include/fixtures/macos_backend_test_hooks.hpp

@@ -199,4 +199,11 @@ namespace lvh::detail::test {
    */
   MacosBackendUtilityResult macos_backend_utilities();
 
+  /**
+   * @brief Read the suppression interval stored on the backend's reusable mouse event.
+   *
+   * @return Suppression interval in seconds, or no value if event-source creation fails.
+   */
+  std::optional<double> macos_backend_mouse_event_suppression_interval();
+
 }  // namespace lvh::detail::test

tests/fixtures/macos_backend_test_hooks.cpp

@@ -123,6 +123,20 @@ namespace lvh::detail::test {
 
   namespace macos = lvh::detail::macos_backend_test;
 
+  std::optional<double> macos_backend_mouse_event_suppression_interval() {
+    macos::MacosInputState state;
+    if (!state.mouse_event) {
+      return std::nullopt;
+    }
+    const auto source = CGEventCreateSourceFromEvent(state.mouse_event);
+    if (!source) {
+      return std::nullopt;
+    }
+    const auto interval = CGEventSourceGetLocalEventsSuppressionInterval(source);
+    CFRelease(source);
+    return interval;
+  }
+
   std::optional<std::uint16_t> macos_backend_key_code(KeyboardKeyCode key_code) {
     const auto mapped = macos::macos_key_code(key_code);
     if (!mapped) {

tests/unit/test_macos_backend.cpp

@@ -21,6 +21,12 @@
  */
 class MacosBackendTest: public MacOSTest {};
 
+TEST_F(MacosBackendTest, DisablesSuppressionForReusableMouseEvent) {
+  const auto interval = lvh::detail::test::macos_backend_mouse_event_suppression_interval();
+  ASSERT_TRUE(interval.has_value());
+  EXPECT_DOUBLE_EQ(*interval, 0.0);
+}
+
 TEST_F(MacosBackendTest, TranslatesKeyboardKeys) {
   EXPECT_EQ(lvh::detail::test::macos_backend_key_code(0x08), kVK_Delete);
   EXPECT_EQ(lvh::detail::test::macos_backend_key_code(0x09), kVK_Tab);