[Qt-interest] Can't set QMainWindow's background for Qt4.3.0 ?

[Kermit Mei]

Hello, in my ui.css, If I wrote:
QMainWindow {background-color: rgb(110, 160, 225);}
Then I can see the background as I set.

But if I worte:

QMainWindow {background-image: url(:/images/background.png); }

I can see nothing. I'm sure that the picture is OK, and it can be load
by other widgets. Always, on Qt4.5.1, it also works well for mainwindow,
but I want to compile it on ARM, and I must use Qt4.3.0.
It doesn't work on Qt4.3.0, why?

Hope any help:)

Thanks.

Kermit