You probably already figured out a solution to this problem, but I noticed that no one answered your post when I was searching for an answer to the same issue. In Construct 2 I used to use the browser object's Execute Javascript function to write: "document.getElementById('my_iframe').style.zIndex = '-1'" That worked very well with Pode's iframe, but doesn't seem to work with the Construct 3 iframe object. I did, however, experiment with stacking two iframes on top of each other. The iframe on top references a URL that has a transparent CSS background layer, and within that background I embedded another Construct 3 project, resizing it and placing it so that you can see the Construct iframe underneath it, if that makes sense. I haven't gone beyond that experiment yet, but I suspect that clicking sprites, etc., in the top Construct window (in the top iframe) can be used to set localStorage keys that you can then read in the lower iframe Construct window in order to get it to respond in a particular way. It's hard to put this all into words, lol....