The Air Plasma Theme in 4.5 gets more transparent with blur turned on which is really nice feature. However I need sometimes to turn off the windows effects (running on battery, watching some movies...) and my problem is that when I turn it on back, KRunner and most of Plasma widgets including panels lose their extra transparency caused by blur, they're just 'normally' transparent but it doesn't look so cool To get it back I need to manually restart Plasma and KRunner which is quite unpleasant.

Is there something I could to about it? Some "automatic" update? Or is it a bug which is going to be fixed in next releases of KDE? Thanks

Hmm... have you tried removing the cache's outside KDE? They can be found at /var/tmp/kdecache-$USER/

wow, it worked, I can now turn off and turn on effects without loosing this extra transparency. The problem is that it lasts only as long as the cache is gone. Once I restart KDE or only Plasma, I have to delete cachce again. So I moved from one manual thing to another

This is definitely a bug in Plasma's caching then. Can you try with KDE 4.6 Beta to see if you can reproduce? If so, can you file a bug report?

I accidentally tried KDE 4.6 Beta when upgrading to 4.5 (I chose wrong repositories), but I can't tell if this problem was there or not. I had enough troubles with downgrading to 4.5 I don't want to go through this process again so I have reported a new bug anyway. In worse case, it has been already fixed.

Little update: I managed to solve this problem. The Air Theme is located (in my opensuse) in /usr/share/kde4/apps/desktoptheme/default. As you can see, among others there are folders dialogs, widgets, opaque and translucent. I simply replaced all files in dialogs, widgets and opaque from those in translucent. It may sound brutal but it works pretty well. I can now turn off and on desktop effects without loosing extra transparency as Plasma always uses the same files. Only defect I have noticed is a big black border around Krunner when desktop effects are turned off. But as I turn desktop effect off only when watching movies it doesn't bother me.

You should backup the Air Theme first in case that something goes wrong. Naturally, this is a temporary solution, this bug will be hopefully fixed in 4.6.