#152 Shadow Traces

[Tsu Jan]

When a window (or dialog) is created and then moved, it leaves a shadow trace in the opposite direction of its movement. The faster is the movement, the more visible is the trace. As a movie is worth ten thousand words, I've attached a screengrab.

I'm using r1710 because you fixed the korganizer issue in it but the problem happened with previous versions too.

[Thomas Luebking]

That would be a bug in kwin (insufficient damage area, bespin only creates and exports the shadow images, painting is completely in kwin)

Please file it at bugs.kde.org and add the output of "qdbus org.kde.kwin /KWin supportInfo" there.

[Tsu Jan]

But Oxygen, Aurorae or QtCurve doesn't have this problem, even with deep shadows. I can see it only with Bespin.

[Thomas Luebking]

They have the shadows inside the decoration widget and at least the oxygen variant is like 16px wider than the visible shadow (the shadow has a very "smooth" fade-out)
Bespin uses the same way for the decoration as for eg. the popups.

The bug means that something undercuts the required update region in kwin, it's therefore a kwin bug. Triggered by bespin, but the bug is definitely in kwin compositing and needs to be fixed there.
I could add a lot of blank space to the shadow pixmap to cover it, but that's no fix.