id	summary	reporter	owner	description	type	status	priority	milestone	component	version	severity	resolution	keywords	cc	focuses	prnumber
42341	Add sandbox attribute to Customizer preview iframe to prevent top-navigation	westonruter	pento	"We go through some hoops to prevent a script in the Customizer preview from attempting to set the `top` window. For example: https://github.com/WordPress/wordpress-develop/blob/2ddcc54/src/wp-includes/js/customize-preview.js#L381-L384

The `iframe` element in HTML5 supports a `sandbox` attribute which we can use to prevent the window from changing the loaded `top` window.

See https://developer.mozilla.org/en-US/docs/Web/HTML/Element/iframe#attr-sandbox"	defect (bug)	closed	normal	5.1	Customize	3.4	normal	fixed	has-patch