diff --git a/src/gui/kernel/qwidget.cpp b/src/gui/kernel/qwidget.cpp
index 1e9d5addc..64d56c61b 100644
--- a/src/gui/kernel/qwidget.cpp
+++ b/src/gui/kernel/qwidget.cpp
@@ -1687,9 +1687,13 @@ static inline void fillRegion(QPainter *painter, const QRegion &rgn, const QBrus
         painter->fillRect(0, 0, painter->device()->width(), painter->device()->height(), brush);
         painter->restore();
     } else {
-        const QVector<QRect> &rects = rgn.rects();
-        for (int i = 0; i < rects.size(); ++i)
-            painter->fillRect(rects.at(i), brush);
+        QPen oldPen = painter->pen();
+        QBrush oldBrush = painter->brush();
+        painter->setPen(Qt::NoPen);
+        painter->setBrush(brush);
+        painter->drawRects(rgn.rects());
+        painter->setBrush(oldBrush);
+        painter->setPen(oldPen);
     }
 }
 
@@ -1715,8 +1719,7 @@ void QWidgetPrivate::paintBackground(QPainter *painter, const QRegion &rgn, int
     const QBrush autoFillBrush = q->palette().brush(q->backgroundRole());
 
     if ((flags & DrawAsRoot) && !(q->autoFillBackground() && autoFillBrush.isOpaque())) {
-        const QBrush bg = q->palette().brush(QPalette::Window);
-        fillRegion(painter, rgn, bg);
+        fillRegion(painter, rgn, q->palette().brush(QPalette::Window));
     }
 
     if (q->autoFillBackground())
diff --git a/src/gui/kernel/qwidget_x11.cpp b/src/gui/kernel/qwidget_x11.cpp
index f46a54c59..ef02265fb 100644
--- a/src/gui/kernel/qwidget_x11.cpp
+++ b/src/gui/kernel/qwidget_x11.cpp
@@ -1256,28 +1256,29 @@ void QWidgetPrivate::updateSystemBackground()
         || q->testAttribute(Qt::WA_NoSystemBackground)
         || q->testAttribute(Qt::WA_UpdatesDisabled)
         || type == Qt::Popup || type == Qt::ToolTip) {
-            if (QX11Info::isCompositingManagerRunning()
-                && q->testAttribute(Qt::WA_TranslucentBackground)
-                && !(q->parent()))
-                XSetWindowBackground(qt_x11Data->display, q->internalWinId(),
-                                     QX11Data::XColorPixel(xinfo.screen(), Qt::transparent));
-            else
-                XSetWindowBackgroundPixmap(qt_x11Data->display, q->internalWinId(), XNone);
+        if (QX11Info::isCompositingManagerRunning()
+            && q->testAttribute(Qt::WA_TranslucentBackground)
+            && !(q->parent())) {
+            XSetWindowBackground(qt_x11Data->display, q->internalWinId(),
+                                 QX11Data::XColorPixel(xinfo.screen(), Qt::transparent));
+        } else {
+            XSetWindowBackgroundPixmap(qt_x11Data->display, q->internalWinId(), XNone);
         }
-    else if (brush.style() == Qt::SolidPattern && brush.isOpaque())
+    } else if (brush.style() == Qt::SolidPattern && brush.isOpaque()) {
         XSetWindowBackground(qt_x11Data->display, q->internalWinId(),
                              QX11Data::XColorPixel(xinfo.screen(), brush.color()));
-    else if (isBackgroundInherited())
+    } else if (isBackgroundInherited()) {
         XSetWindowBackgroundPixmap(qt_x11Data->display, q->internalWinId(), ParentRelative);
-    else if (brush.style() == Qt::TexturePattern) {
+    } else if (brush.style() == Qt::TexturePattern) {
         const Qt::HANDLE bgpixmap = brush.texture().toX11Pixmap();
         XSetWindowBackgroundPixmap(qt_x11Data->display, q->internalWinId(), bgpixmap);
         if (bgpixmap) {
             XFreePixmap(qt_x11Data->display, bgpixmap);
         }
-    } else
+    } else {
         XSetWindowBackground(qt_x11Data->display, q->internalWinId(),
                              QX11Data::XColorPixel(xinfo.screen(), brush.color()));
+    }
 }
 
 #ifndef QT_NO_CURSOR