Mine

--- bball.cpp.orig      2008-01-16 10:47:20.000000000 +1000
+++ bball.cpp   2008-01-16 13:51:53.000000000 +1000
@@ -24,20 +24,21 @@
 #include <QMessageBox>
 #include <qdesktopwidget.h>

-
 #include <plasma/svg.h>
 #include <plasma/theme.h>
 #include <plasma/phase.h>

+const int ball_size = 100;
+
 using namespace Plasma;

 bball::bball(QObject *parent, const QVariantList &args)
     : Plasma::Applet(parent, args),
-    m_size(200,200),
+    m_size(ball_size, ball_size),
     m_ball_svg("widgets/bball", this)
 {
        m_ball_svg.setContentType(Plasma::Svg::SingleImage);
-       m_position = QRectF(100,100, 100, 100);
+       m_position = QRectF(ball_size, ball_size, ball_size, ball_size);
        QDesktopWidget* desktop = new QDesktopWidget();
        m_screen = desktop->availableGeometry();

@@ -119,6 +120,10 @@

 void bball::paintInterface(QPainter *p, const QStyleOptionGraphicsItem *option, const QRect &contentsRect)
 {
+       Q_UNUSED(option);
+
+       setDrawStandardBackground(false);
+
        p->setRenderHint(QPainter::SmoothPixmapTransform);
        p->setRenderHint(QPainter::Antialiasing);

@@ -138,6 +143,8 @@

 void bball::mouseReleaseEvent(QGraphicsSceneMouseEvent* event)
 {
+       Q_UNUSED(event);
+
        m_x_vel = (m_mouse - m_old_mouse).x();
        m_y_vel = (m_mouse - m_old_mouse).y();
        m_mouse_pressed = false;