save memery by drawing directly onto screen

and use the helper routine to correctly draw gradient behind buttons

svn path=/trunk/KDE/kdebase/workspace/; revision=803670

clients/oxygen/oxygenbutton.cpp

@@ -156,6 +156,9 @@ void OxygenButton::paintEvent(QPaintEvent *)
     QPainter painter(this);
     QPalette pal = palette(); // de-const-ify
 
+
+    helper_.renderWindowBackground(&painter, this->rect(), this);
+
     if (type_ == ButtonMenu) {
         // we paint the mini icon (which is 16 pixels high)
         int dx = (width() - 16) / 2;

clients/oxygen/oxygenclient.cpp

@@ -89,10 +89,6 @@ void OxygenClient::init()
 
     widget()->setAutoFillBackground(false);
     widget()->setAttribute(Qt::WA_OpaquePaintEvent);
-#ifdef __GNUC__
-#warning This wastes quite a lot of memory.
-#endif
-    widget()->setAttribute(Qt::WA_PaintOnScreen, false);
 }
 
 bool OxygenClient::decorationBehaviour(DecorationBehaviour behaviour) const