If eventKind is COREWEBVIEW2_MOUSE_EVENT_KIND_HORIZONTAL_WHEEL or COREWEBVIEW2_MOUSE_EVENT_KIND_WHEEL, then mouseData specifies the amount of wheel movement. A positive value indicates that the wheel was rotated forward, away from the user; a negative value indicates that the wheel was rotated backward, toward the user. One wheel click is defined as WHEEL_DELTA, which is 120. If eventKind is COREWEBVIEW2_MOUSE_EVENT_KIND_X_BUTTON_DOUBLE_CLICK COREWEBVIEW2_MOUSE_EVENT_KIND_X_BUTTON_DOWN, or COREWEBVIEW2_MOUSE_EVENT_KIND_X_BUTTON_UP, then mouseData specifies which X buttons were pressed or released. This value should be 1 if the first X button is pressed/released and 2 if the second X button is pressed/released. If eventKind is COREWEBVIEW2_MOUSE_EVENT_KIND_LEAVE, then virtualKeys, mouseData, and point should all be zero. If eventKind is any other value, then mouseData should be zero. Point is expected to be in the client coordinate space of the WebView. To track mouse events that start in the WebView and can potentially move outside of the WebView and host application, calling SetCapture and ReleaseCapture is recommended. To dismiss hover popups, it is also recommended to send COREWEBVIEW2_MOUSE_EVENT_KIND_LEAVE messages. \snippet ViewComponent.cpp SendMouseInput