OS: Chrome
Version: 61.0.3163.38

1. Enable ChromeVox with Ctrl Alt Z
2. Press Ctrl P to open print 
3. Use ChromeVox (Search + Right) to navigate to the Change button to then add a printer. Once you get to Save as PDF, press Search + Space and the Add Printers dialog should appear.

Right now, once that dialog opens, then focus SHOULD go directly into that dialog, starting with "Add Printers". 

Instead, focus goes back up to the top of the UI that is behind and greyed out. You can eventually get to the dialog, but it takes a long time and isn't intuitive. Focus should go directly there, and you should have to either press one of the buttons or press escape to be able to access anything else -- focus should be trapped until you take action.