Background blur frosted glass effect API for toolkits and applications
Feature summary
See title. Like sidebar below:
How would you like it to work
Basically, an app would request to Mutter for its background to be blurred with a specific radius, (transparent) colour and saturation. Then, it would leave the necessary pixels transparent to show through frosted glass effect.
Relevant links, screenshots, screencasts etc.
I think Kwin supports this also.