Version:            (using KDE 4.1.0)
Installed from:    Unspecified Linux

Note: composite must be enabled in order to see this effect.

When showing and hiding the dashboard with composite enabled, there is a nice fading animation that darkens everything and fades the desktop plasmoids to the top. As far as I can tell, this effect is achieved by fading in a partially transparent black window on top of everything else, and then simultaneously fading in a copy of each plasmoid in on top of that. This results in a momentary dimming of all plasmoids during the animation. 

As best as I can determine, the reason is this: during the animation (and maybe as long as the dashboard is shown?*), two copies of each plasmoid are drawn: one at the bottom, in the normal desktop layer, and one on top, in the dashboard layer. When the dashboard animation begins, the plasmoids on the desktop layer will start to fade to black along with everything else. Meanwhile, their copies on the dashboard layer will begin to fade in. Therefore, halfway through this animation, you will be looking through a partially transparent copy of each plasmoid at a partially darkened copy of it. This results in a dimming effect.

The reason for effect is hard to describe, but the effect itself is easy to reproduce. To observe the easily, place one large plasmoid, such as a Picture Frame, on your desktop, and minimize all windows. Then, make a "telescope" with your hand to limit your field of view entirely to the area of the plasmoid. This will ensure that the background fade will not interfere with your observation. Now, activate the dashboard, and observe the plasmoid momentarily dim and then brighten again.

I'm not sure how to fix this. It would seem to require a circular stacking order: dashboard above normal windows above desktop above dashboard. I gather that the desired effect is that the plasmoids should appear to diffuse through the normal windows to the top. One potential way to make it work would be to darken each main window individually (as well as the desktop background) at the same time (instead of making one big dark window appear in front), but I assume that simultaneously and indivually changing each window's brightness while fading in a bunch of plasmoids would not have good performance.


* If this is true, then all partially transparent plasmoids not obscured by normal windows would become less transparent than normal while the dashboard is shown, since you would be looking through two copies of the plasmoid. I can't tell visually whether this is in fact happening.