KDE SC 4.5 will bring back blurring, but for OpenGL only.
Plasma doesn't use this effect and I don't recommend to use it for "normal" windows (in combination with Bespin or ?QtCurve?)
Since XRender doesn't know accelerated pixel manipulation (like stencil shaders in glsl) this solution "fakes" blurring by painting the area several times with a reduced alpha value.
This is slow, therefore the result is cached. Also blurring is skipped for moving/resizing windows and during fullscreen effects (like "present windows"). It should be sufficient for your panel or the info popus, though.
· KDE Software Compilation
What's New in This Release: [ read full changelog ]
· version for KDE >= 4.7
· some improvements/fixes