UserAgent: Mozilla/5.0 (X11; CrOS x86_64 11021.56.0) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/70.0.3538.76 Safari/537.36
Platform: 11021.56.0 (Official Build) stable-channel eve

Steps to reproduce the problem:
1. Attach Monitor and Extend Display
2. Open VS Code (or Chrome or any other app) in Crostini and put onto the External Monitor
3. Take an action to save a file that will result in a File Save window opening (same is true for Confirmation modals upon delete)

What is the expected behavior?
Window/Modal should appear in the center of the app displayed on the External Monitor

What went wrong?
Window/Modal does not appear on either display and instead is placed in an unviewable area of the display

Did this work before? N/A 

Chrome version: 70.0.3538.76  Channel: stable
OS Version: 11021.56.0
Flash Version: 31.0.0.122 

Once this occurs, you can unplug the external monitor, rotate the screen and then rotate it back, and the window/modal will be within the viewable area of the display.