border color is wrong with "plastique" style in Qt4.2.3

[alfa_wu]

Machine: Linux 2.4.21-4.ELsmp #1 SMP
When I run
~/qt-x11-commercial-src-4.2.3/examples/widgets/lineedits/lineedits -style plastique
I find the the border color of "lineEdit" widget is different from Qt4.1.3's.
The border is thick black, and look ugly.

Is it really Qt4.2.3 bug?
If yes, how can we fixed?
If no, how can we avoid it ?

The Qt4.2.3 Library configuration option is
configure -static -debug -no-fontconfig -no-xrandr -no-glib -no-iconv

By the way,
The same condition on Solaris machine.

[Bitto]

Since 4.2, Plastique uses alpha mapping, which requires XRender on X11. Solaris does support X servers with XRender support, IIRC. In 4.1, Plastique didn't use alpha mapping so it looked better on older X servers. We used hacks to fake semi-transparent behavior, but unfortunately those hacks made it impossible for Plastique to support gradients and texture brushes. For the simplest case, in 4.1 Plastique was the only style that had real problems with any palette changes, such as making a button red.

In 4.2, Plastique supports all palette features, gradients and textures. But because it needs alpha mapping, it doesn't look good on older X servers.

[Brandybuck]

I've seen something like this before on occasion. I don't know if it is the same problem though. Twice I have had problems installing Qt, where the the widgets looked very bad, almost as if the display were set to 8 bit color. In both cases I reinstalled Qt and the problem went away.