The ‘focus‘ word has many meanings, ranging from the optical concept of ‘good convergence of light rays generated by an object’ to the cognitive process of directing the attention to a particular target while ignoring other targets.
Now the interesting part: this concept can be used in computers too, especially in user interfaces, to direct the user to relevant information or to help him through a step-by-step process. How to do that? Since every image you see on screen is ‘on focus’ by default, you can easily unfocus unuseful information.
Blurring is the act of altering images so they appear out of focus. My Maestro and other illustriuos people already talked extensively about this topic here on planet KDE. However you don’t improve the world until a technology becomes available to everybody, right?
Then some days ago I read on notmart’s blog that plasma and kwin supported blurring the background on windows.. so I rebuilt KDE4 svn, restarted it, and… boy.. does it make a difference!