The kwin composite extension now supports blurring for better reading. However, the hardware needs for this feature are quite high.
The new feature by Rivo Laks was mentioned in the last commit-digest, issue 56:
Blur effects blurs out background of translucent windows, thus improving e.g. readability of text in such windows.
The reason to have this functionality comes clear if you compare the following two screenshots:
Both images show a transparent window in front of another window. In the first image the text of the active window is difficult to read because the text of the underlying window disturbs the reading. The second image now has a blur effect activated, making it much easier to read the text of the transparent window.
You can now ask how much sense it makes to have a transparent window when you want to read text anyway, but this is about eye candy, and several people like it that way. I even impressed my (totally windows only) room mate two days ago by just showing some funky Beryl things.
Anyway, whether you like it or not, the implementation of the blur effect is quite hardware intensive. As Rivo Laks points out in an additional e-mail:
It uses shaders and render targets, so ATM it needs GeForce 6000 or up (not so
sure about ATI cards, Radeon x500 or something and up may work).
Once I get our GLRenderTarget to work with ARB_texture_rectangle, it will also
work on cards not supporting NPOT textures, that is GeForce 5000 / Radeon
9500 and up. I’m not sure if those cards are fast enough for everyday usage
That’s quite a lot – I wonder which Intel chips (which have the best free drivers available) will work with that.
I doubt that most people have such powerful graphic cards, so I think many people will not see this new feature anytime soon…