• Steam client version (build number or date): July 2 2019
• Distribution (e.g. Ubuntu): Arch
• Opted into Steam client beta?: [Yes/No] Yes
• Have you checked for system updates?: [Yes/No] Yes

https://gist.github.com/shoober420/1215c40214cf70e1fabb760b5bd2a341

Please describe your issue in as much detail as possible:

Under Settings > Controller, if a user clicks on "Big Picture Configuration", "Desktop Configuration", or "Guide Button Chord Configuration" repeatedly with no controller plugged in, multiple Big Picture windows are spawned, some simply black screens.

The Big Picture Controller config screens should be limited to one, to avoid all these windows opened, and unnecessary clutter of Big Picture windows. For example, if a user clicks on "Big Picture Configuration", "Desktop Configuration", or "Guide Button Chord Configuration" while the previous config window is still open, it closes the previous instance of Big Picture in favor of the new one.

Steps for reproducing this issue:

1. Go to Settings > Controller
2. Click on Big Picture Configuration", "Desktop Configuration", or "Guide Button Chord Configuration" repeatedly
3. Big Picture windows are spammed on the screen, most simply black screens