>> GroupBox like this in TDEPowersave? At first glance, I did not see any
>> problem. However, when I tried KUIViewer I see a problem after switch to
>> QtCurve style. Until then, in all styles GroupBox displays fine. From the
>> first switch to QtCurve in all styles is GroupBox displayed without a
>> frame.

> I have one surprising finding - selecting style QtCurve in TDE 3.5.13.2 leads
> to the identical disappearance frames of GroupBoxes! It seems that it's not a
> new bug. And also that is related to QtCurve.

Ah ah!! I use QtCurve as default style on my system, while on my test VM I use Plastik.
It must be something triggered by QtCurve, but there must also be something else because as you said after the first switch to QtCurve, the problem remains also after switching to other styles.

I will open a bug report for this.
Given that the problem was also in 3.5.13.2, should we add this bug to the v14.0.0 bug list or should we address this after that (perhaps in a following maintenance release)?

Cheers
  Michele