Other than the focused theme is set after installation, if more Color themes are opened in separate tabs

[Softvision-AndreeaCupsa]

[Affected versions]:

• Firefox 60.0.2 and up

[Affected Platforms]:

• All Windows
• All Mac
• All Linux

[Steps to reproduce]:

1. Open Firefox and navigate to a "Firefox Color" shared theme.
2. Open a new tab and navigate to another "Firefox Color" shared theme.
3. Focus the first tab and observe the theme aspect.
4. Click the "Install Firefox Color" button and follow the flow in order to succesfully install the add-on.
5. Observe the applied theme in comparison with the one from step 2.

[Expected result]:

• Add-on is succesfully installed and the theme from the focused tab at step 2 is set.

[Actual result]:

• Add-on is succesfully installed but a theme from the second tab is set.

[Notes]:

• During installation the themes from the other tab is briefly displayed.
• This issue is also reproducible with preset themes.
• Links for a few shared themes:
  • https://tinyurl.com/yaff29ez
  • https://tinyurl.com/yc6tan3x
  • https://tinyurl.com/ybzwlnuc
  • https://tinyurl.com/ybx5vlc3
• Attached a screen recording of the issue:

[johngruen]

Requires stewing

[johngruen]

So this would also affect session restore...

Maybe we check for multiple color tabs on startup and pick either focused or none>