Thanks for your response. Just to clarify, we are only using the Tobii Core SDK in both cases. In fact, the WinForm app doesn’t even link to the older EyeX SDK. It’s just a window hosting the Wpf UserControl. In both cases, the Wpf UserControl only links with the Tobii Core SDK. The only difference is: In case #1, the Wpf UserControl is embedded in a WinForm and in case #2, it is embedded in a Wpf form. The gaze events don’t trigger in Case #1 and they do in case #2.