It also uses JesseJoh's HTML Elements Pack: http://www.scirra.com/forum/plugin-jessejohs-html-elements-pack_topic47084.html
The problem only exists when two conditions are met;
- Fullscreen in browser is set to SCALE
- Unbounded Scrolling is set to ENABLED/TRUE
Only when these two options are enabled, the iFrame object specifically, seems to be bound to the coordinates of the browser window itself rather than the layout/canvas. Using any means to move the object results in additional problems, causing the object to move unpredictably around the browser window (or even outside of it!) while using the mouse to resize the browser window at runtime.
Using events to "create iFrame at X,Y" will also result in the object not appearing in the correct position.
The problem is more obvious on a layout that is portrait in orientation rather than a perfect aspect landscape layout.
After talking with Kyat and Newt in chat... we have all deduced there is a problem here somewhere. Kyat suggests it may be in the code from your button object, as JesseJoh seems to have used that portion of code in the iframe positioning. Come to think of it, I believe the buttons also suffer this same problem so it could indeed be related.
If you need any more info, let me know. Thanks Ashley :D
Added a button to the layout as well, and yes... it's the same problem with the button as well!