I’m one of those discussed in this post that is developing Xojo Apps which are then embedded into other web sites with an IFRAME:
I have a specific issue: obviously the Xojo App inside the IFRAME makes the web page scroll down so that that IFRAME is in a visible area. Since the app in question here is a widget which is displayed at the bottom of the page, the browser always scrolls down to the bottom for every click the users makes.
Do you have anything in the iframe that set the focus?
I have seen page scrolls (without iframe) if the control that get the focus is not in the visible area.
In other words, try a Xojo webapp in the iframe that don’t have/set focus and see if it still scroll down.