Chrome OS Version: Version 64.0.3282.190 (Official Build) (32-bit)
Chrome OS Platform: bob

Please specify Cr-* of the system to which this bug/feature applies (add
the label below).

Steps To Reproduce:
(1) Go to Settings, Network, Add OpenVPN / L2TP…
(2) Paste in hostname from wherever you got it (probably a setup guide from a VPN provider's website.
(3) Try to alt-tab back to the website to get the rest of the setup info (pre-shared key, username, password, etc.)

Expected Result:

Like almost any other UI in Chrome OS, be able to switch windows.

Actual Result:

This dialog appears to be system-modal, meaning that the user can't use computers during this transaction and must instead commit all information to memory or else write everything down on a piece of paper.

How frequently does this problem reproduce? Always

What is the impact to the user, and is there a workaround? If so, what is
it? Write down all the information on a piece of paper.