Feature request: Add an option to put image background under Settings/Add-ons page sidebar

[Aleksandra0056]

Is your feature request related to a problem?

I think, that there should be an option to make the Settings page/Add-ons page sidebar have a background image instead of a monochrome colour background (white/black).

The only problem would be, that users would manually measure the height of the sidebar since everyone has different toolbars settings (bookmarks bar, title bar or third-party toolbars) which would make the height of the sidebar image dynamic, but that is a problem for users themselves and not for the actual implementation I think.

The solution I'd like

Add an option to the user.js/about:config to allow the settings sidebar to use a background image for better customisation.

Screenshots or video

Affected sidebars:

Settings page sidebar:

Add-ons page sidebar:

Alternatives I've considered

No response

Additional context

No response

[Aleksandra0056]

This is where I found inspiration for this feature request.

Windows Vista Control Panel sidebar:

Windows 7 Beta Control Panel sidebar:

Windows 7 RTM Control Panel sidebar: