Created attachment 8737747 [details] Screen Shot 2016-04-04 at 15.31.10.png 1. Open http://people.mozilla.org/~sarentz/t/onprint.html in a new private tab 2. Press on 'Print this age' > The 'Printer Options' dialog opens 3. Go to the app switcher Expected: The 'Printer Option' dialog is hidden Actual: The 'Printer Option' dialog, which contains a capture of the page open in pb mode, is visible in the app switcher
Thats a system dialog, so you can't hide it by changing its opacity. It might be possible to dismiss the dialog somehow when you enter the task switcher.