Resizable dialog is not working inside a page with some scroll

This fix is changing the way we set the position of the resizable overlay, using the real position of the element insted of its position inside the viewport.
In your code, ```Timer.addCallback``` has an empty callback function and is not actually doing anything here, the delay isn't applied to anything.  If you need to add the delay you can create a callback method for the code you want to execute after a certain delay, otherwise, If you don't need a delay you can remove the ```Timer.addCallback``` from here.