The following example shows a rounded and smoothed rectangle when a gradient is used. But this cannot be correct?
It does not help to set smooth: false either.
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import Qt 4.7

Rectangle {
width:300; height:200

Rectangle {
x: 50; y:50
width: 50
height: 50
gradient: Gradient {
GradientStop

GradientStop

}
border.width: 4
smooth: false
}
}