Allow to manually specify a theme to apply to a section of an app

[skjnldsv]

This allow apps to add [data-theme-dark] (or whatever theme they want) to force a specific theme to apply to a section of an app.

e.g, we want to force the image editor to have a dark theme, no matter what current theme the user have.
Just adding [data-theme-dark] to the editor root element will make the entire editor using the dark theme.

Peek.16-08-2022.14-49.mp4

[juliusknorr]

Nice 👍

That is actually quite useful as well for collabora where the dark mode is currently still not available, but we need to pass over our css variables for theming.

[skjnldsv]

One pitfall to keep in mind though:
The only issue is that it will fully override the current theme. So if you had for example the highcontrast-theme enabled, it will use the dark-theme, not dark-highcontrast-theme

But that can be fixed on the app side by check which current theme is enabled I guess 🤔
Any other idea to fix/help that use-case?