Border radius unix/windows

Hey there,
sry for my 3rd thread today, but I've been working on my GUI all day and I've been able to accomplish quite a bit.

Now here is my problem:

The border radius works just fine on the windows machine, while it does not on the unix.
Also the windows client is v 4.7.0 and the unix one 4.2.1.

The stylesheet:
#widget_2{
background: white;
border: 2px solid black;
border-radius: 20px;
}

Thanks
(It is really hard to finde people with the same problems on QT with google ;) )

Are stylesheets available in Qt 4.2.1? I think they are introduced a lot later.

stylesheets are available. For example changing the background works just fine and the designer has the option to add stylesheets.