Hi @tw2018 and thanks for your query. Could you kindly clarify which technology you are using to render a window and under which programming platform?
For instance, if you are using WPF under .NET then the Tobii Core SDK Interaction API would seem to be ideal for your needs and indeed we have several sample application you can download and run @ https://github.com/Tobii/interaction-samples
Within these samples is demonstrated how to programmatically asign an object within a window to be ‘gaze aware’.
Please kindly have a look at these and let us know if this is what you are looking for. Otherwise, let us know if further detail of your setup including hardware, SDK version, etc and we will do our best to help you out!