Merge branch '4.7' of scm.dev.nokia.troll.no:qt/oslo-staging-2 into 4.7-integration

* '4.7' of scm.dev.nokia.troll.no:qt/oslo-staging-2:
  QPainter not restored correctly in Graphics View.
  Setting QGraphicsItem::ItemClipsChildrenToShape forces ItemClipsToShape
  Fix compilation
  Fixed drawing of QPixmaps with masks in the GL 2 and X11 engines.
  Fix warning on MSVC
  QThread: make sure start works even if called after exit
  Revert "Fixed painter path drawing on FBO without stencil buffer."
  Fix a crash with D&d on mingw
  Revert "Keep other text format with QTextOption::SuppressColors tag on"
  Fixed stencil buffer on FBOs with OpenGL ES.
  Keep other text format with QTextOption::SuppressColors tag on
  QTreeView: do not scroll to top if last item is removed

15 files changed, 199 insertions, 112 deletions

diff --git a/src/corelib/thread/qthread_unix.cpp b/src/corelib/thread/qthread_unix.cpp
index 2824e15..a7601b6 100644
--- a/src/corelib/thread/qthread_unix.cpp
+++ b/src/corelib/thread/qthread_unix.cpp
@@ -514,6 +514,8 @@ void QThread::start(Priority priority)
     d->running = true;
     d->finished = false;
     d->terminated = false;
+    d->returnCode = 0;
+    d->exited = false;
 
     pthread_attr_t attr;
     pthread_attr_init(&attr);
diff --git a/src/corelib/thread/qthread_win.cpp b/src/corelib/thread/qthread_win.cpp
index 37d5b87..f0cbe8d 100644
--- a/src/corelib/thread/qthread_win.cpp
+++ b/src/corelib/thread/qthread_win.cpp
@@ -405,6 +405,8 @@ void QThread::start(Priority priority)
     d->running = true;
     d->finished = false;
     d->terminated = false;
+    d->exited = false;
+    d->returnCode = 0;
 
     /*
       NOTE: we create the thread in the suspended state, set the
diff --git a/src/gui/graphicsview/qgraphicsscene.cpp b/src/gui/graphicsview/qgraphicsscene.cpp
index 54fdf3f..8dc15bf 100644
--- a/src/gui/graphicsview/qgraphicsscene.cpp
+++ b/src/gui/graphicsview/qgraphicsscene.cpp
@@ -4814,6 +4814,27 @@ void QGraphicsScenePrivate::drawSubtreeRecursive(QGraphicsItem *item, QPainter *
     }
 }
 
+static inline void setClip(QPainter *painter, QGraphicsItem *item)
+{
+    painter->save();
+    QRectF clipRect;
+    const QPainterPath clipPath(item->shape());
+    if (QPathClipper::pathToRect(clipPath, &clipRect))
+        painter->setClipRect(clipRect, Qt::IntersectClip);
+    else
+        painter->setClipPath(clipPath, Qt::IntersectClip);
+}
+
+static inline void setWorldTransform(QPainter *painter, const QTransform *const transformPtr,
+                                     const QTransform *effectTransform)
+{
+    Q_ASSERT(transformPtr);
+    if (effectTransform)
+        painter->setWorldTransform(*transformPtr * *effectTransform);
+    else
+        painter->setWorldTransform(*transformPtr);
+}
+
 void QGraphicsScenePrivate::draw(QGraphicsItem *item, QPainter *painter, const QTransform *const viewTransform,
                                  const QTransform *const transformPtr, QRegion *exposedRegion, QWidget *widget,
                                  qreal opacity, const QTransform *effectTransform,
@@ -4822,36 +4843,37 @@ void QGraphicsScenePrivate::draw(QGraphicsItem *item, QPainter *painter, const Q
     const bool itemIsFullyTransparent = QGraphicsItemPrivate::isOpacityNull(opacity);
     const bool itemClipsChildrenToShape = (item->d_ptr->flags & QGraphicsItem::ItemClipsChildrenToShape);
     const bool itemHasChildren = !item->d_ptr->children.isEmpty();
+    bool setChildClip = itemClipsChildrenToShape;
+    bool itemHasChildrenStackedBehind = false;
 
     int i = 0;
     if (itemHasChildren) {
+        if (itemClipsChildrenToShape)
+            setWorldTransform(painter, transformPtr, effectTransform);
+
         item->d_ptr->ensureSortedChildren();
+        // Items with the 'ItemStacksBehindParent' flag are put in front of the list
+        // so all we have to do is to check the first item.
+        itemHasChildrenStackedBehind = (item->d_ptr->children.at(0)->d_ptr->flags
+                                        & QGraphicsItem::ItemStacksBehindParent);
 
-        if (itemClipsChildrenToShape) {
-            painter->save();
-            Q_ASSERT(transformPtr);
-            if (effectTransform)
-                painter->setWorldTransform(*transformPtr * *effectTransform);
-            else
-                painter->setWorldTransform(*transformPtr);
-            QRectF clipRect;
-            const QPainterPath clipPath(item->shape());
-            if (QPathClipper::pathToRect(clipPath, &clipRect))
-                painter->setClipRect(clipRect, Qt::IntersectClip);
-            else
-                painter->setClipPath(clipPath, Qt::IntersectClip);
-        }
+        if (itemHasChildrenStackedBehind) {
+            if (itemClipsChildrenToShape) {
+                setClip(painter, item);
+                setChildClip = false;
+            }
 
-        // Draw children behind
-        for (i = 0; i < item->d_ptr->children.size(); ++i) {
-            QGraphicsItem *child = item->d_ptr->children.at(i);
-            if (wasDirtyParentSceneTransform)
-                child->d_ptr->dirtySceneTransform = 1;
-            if (!(child->d_ptr->flags & QGraphicsItem::ItemStacksBehindParent))
-                break;
-            if (itemIsFullyTransparent && !(child->d_ptr->flags & QGraphicsItem::ItemIgnoresParentOpacity))
-                continue;
-            drawSubtreeRecursive(child, painter, viewTransform, exposedRegion, widget, opacity, effectTransform);
+            // Draw children behind
+            for (i = 0; i < item->d_ptr->children.size(); ++i) {
+                QGraphicsItem *child = item->d_ptr->children.at(i);
+                if (wasDirtyParentSceneTransform)
+                    child->d_ptr->dirtySceneTransform = 1;
+                if (!(child->d_ptr->flags & QGraphicsItem::ItemStacksBehindParent))
+                    break;
+                if (itemIsFullyTransparent && !(child->d_ptr->flags & QGraphicsItem::ItemIgnoresParentOpacity))
+                    continue;
+                drawSubtreeRecursive(child, painter, viewTransform, exposedRegion, widget, opacity, effectTransform);
+            }
         }
     }
 
@@ -4864,38 +4886,50 @@ void QGraphicsScenePrivate::draw(QGraphicsItem *item, QPainter *painter, const Q
                                      ? *exposedRegion : QRegion(), exposedRegion == 0);
 
         const bool itemClipsToShape = item->d_ptr->flags & QGraphicsItem::ItemClipsToShape;
-        const bool savePainter = itemClipsToShape || painterStateProtection;
-        if (savePainter)
-            painter->save();
+        bool restorePainterClip = false;
 
         if (!itemHasChildren || !itemClipsChildrenToShape) {
-            if (effectTransform)
-                painter->setWorldTransform(*transformPtr * *effectTransform);
-            else
-                painter->setWorldTransform(*transformPtr);
+            // Item does not have children or clip children to shape.
+            setWorldTransform(painter, transformPtr, effectTransform);
+            if ((restorePainterClip = itemClipsToShape))
+                setClip(painter, item);
+        } else if (itemHasChildrenStackedBehind){
+            // Item clips children to shape and has children stacked behind, which means
+            // the painter is already clipped to the item's shape.
+            if (itemClipsToShape) {
+                // The clip is already correct. Ensure correct world transform.
+                setWorldTransform(painter, transformPtr, effectTransform);
+            } else {
+                // Remove clip (this also ensures correct world transform).
+                painter->restore();
+                setChildClip = true;
+            }
+        } else if (itemClipsToShape) {
+            // Item clips children and itself to shape. It does not have hildren stacked
+            // behind, which means the clip has not yet been set. We set it now and re-use it
+            // for the children.
+            setClip(painter, item);
+            setChildClip = false;
         }
 
-        if (itemClipsToShape) {
-            QRectF clipRect;
-            const QPainterPath clipPath(item->shape());
-            if (QPathClipper::pathToRect(clipPath, &clipRect))
-                painter->setClipRect(clipRect, Qt::IntersectClip);
-            else
-                painter->setClipPath(clipPath, Qt::IntersectClip);
-        }
-        painter->setOpacity(opacity);
+        if (painterStateProtection && !restorePainterClip)
+            painter->save();
 
+        painter->setOpacity(opacity);
         if (!item->d_ptr->cacheMode && !item->d_ptr->isWidget)
             item->paint(painter, &styleOptionTmp, widget);
         else
             drawItemHelper(item, painter, &styleOptionTmp, widget, painterStateProtection);
 
-        if (savePainter)
+        if (painterStateProtection || restorePainterClip)
             painter->restore();
     }
 
     // Draw children in front
     if (itemHasChildren) {
+        if (setChildClip)
+            setClip(painter, item);
+
         for (; i < item->d_ptr->children.size(); ++i) {
             QGraphicsItem *child = item->d_ptr->children.at(i);
             if (wasDirtyParentSceneTransform)
@@ -4904,11 +4938,11 @@ void QGraphicsScenePrivate::draw(QGraphicsItem *item, QPainter *painter, const Q
                 continue;
             drawSubtreeRecursive(child, painter, viewTransform, exposedRegion, widget, opacity, effectTransform);
         }
-    }
 
-    // Restore child clip
-    if (itemHasChildren && itemClipsChildrenToShape)
-        painter->restore();
+        // Restore child clip
+        if (itemClipsChildrenToShape)
+            painter->restore();
+    }
 }
 
 void QGraphicsScenePrivate::markDirty(QGraphicsItem *item, const QRectF &rect, bool invalidateChildren,
@@ -5271,6 +5305,7 @@ void QGraphicsScene::drawItems(QPainter *painter,
     if (!d->unpolishedItems.isEmpty())
         d->_q_polishItems();
 
+    const qreal opacity = painter->opacity();
     QTransform viewTransform = painter->worldTransform();
     Q_UNUSED(options);
 
@@ -5304,6 +5339,7 @@ void QGraphicsScene::drawItems(QPainter *painter,
         topLevelItems.at(i)->d_ptr->itemDiscovered = 0;
 
     painter->setWorldTransform(viewTransform);
+    painter->setOpacity(opacity);
 }
 
 /*!
diff --git a/src/gui/graphicsview/qgraphicsview.cpp b/src/gui/graphicsview/qgraphicsview.cpp
index c8aca80..a566c8e 100644
--- a/src/gui/graphicsview/qgraphicsview.cpp
+++ b/src/gui/graphicsview/qgraphicsview.cpp
@@ -3475,7 +3475,8 @@ void QGraphicsView::paintEvent(QPaintEvent *event)
         // IndirectPainting (the else branch), because in that case we always save()
         // and restore() in QGraphicsScene::drawItems().
         if (!d->scene->d_func()->painterStateProtection)
-            painter.setWorldTransform(viewTransform);
+            painter.setOpacity(1.0);
+        painter.setWorldTransform(viewTransform);
     } else {
         // Make sure we don't have unpolished items before we draw
         if (!d->scene->d_func()->unpolishedItems.isEmpty())
diff --git a/src/gui/image/qpixmap_x11.cpp b/src/gui/image/qpixmap_x11.cpp
index 3d9c363..32676ba 100644
--- a/src/gui/image/qpixmap_x11.cpp
+++ b/src/gui/image/qpixmap_x11.cpp
@@ -1321,6 +1321,15 @@ QBitmap QX11PixmapData::mask() const
     return mask;
 }
 
+bool QX11PixmapData::hasMask() const
+{
+    return
+#ifndef QT_NO_XRENDER
+        (picture && d == 32) ||
+#endif
+        (d == 1) || x11_mask;
+}
+
 
 /*!
     Sets a mask bitmap.
@@ -1549,7 +1558,7 @@ QImage QX11PixmapData::toImage(const QRect &rect) const
     if (!xiWrapper.xi)
         return QImage();
 
-    if (canTakeQImageFromXImage(xiWrapper))
+    if (!x11_mask && canTakeQImageFromXImage(xiWrapper))
         return takeQImageFromXImage(xiWrapper);
 
     QImage image = toImage(xiWrapper, rect);
diff --git a/src/gui/image/qpixmap_x11_p.h b/src/gui/image/qpixmap_x11_p.h
index 821fb69..fcad1a2 100644
--- a/src/gui/image/qpixmap_x11_p.h
+++ b/src/gui/image/qpixmap_x11_p.h
@@ -82,6 +82,7 @@ public:
 
     void fill(const QColor &color);
     QBitmap mask() const;
+    bool hasMask() const;
     void setMask(const QBitmap &mask);
     bool hasAlphaChannel() const;
     void setAlphaChannel(const QPixmap &alphaChannel);
diff --git a/src/gui/image/qpixmapdata.cpp b/src/gui/image/qpixmapdata.cpp
index ef1f6c4..2813ed1 100644
--- a/src/gui/image/qpixmapdata.cpp
+++ b/src/gui/image/qpixmapdata.cpp
@@ -239,6 +239,11 @@ QBitmap QPixmapData::mask() const
     return QBitmap::fromImage(mask);
 }
 
+bool QPixmapData::hasMask() const
+{
+    return hasAlphaChannel();
+}
+
 QPixmap QPixmapData::transformed(const QTransform &matrix,
                                  Qt::TransformationMode mode) const
 {
diff --git a/src/gui/image/qpixmapdata_p.h b/src/gui/image/qpixmapdata_p.h
index ec62b0b..c341930 100644
--- a/src/gui/image/qpixmapdata_p.h
+++ b/src/gui/image/qpixmapdata_p.h
@@ -99,6 +99,7 @@ public:
     virtual int metric(QPaintDevice::PaintDeviceMetric metric) const = 0;
     virtual void fill(const QColor &color) = 0;
     virtual QBitmap mask() const;
+    virtual bool hasMask() const;
     virtual void setMask(const QBitmap &mask);
     virtual bool hasAlphaChannel() const = 0;
     virtual QPixmap transformed(const QTransform &matrix,
diff --git a/src/gui/itemviews/qtreeview.cpp b/src/gui/itemviews/qtreeview.cpp
index b797776..40b51fe 100644
--- a/src/gui/itemviews/qtreeview.cpp
+++ b/src/gui/itemviews/qtreeview.cpp
@@ -3435,6 +3435,10 @@ void QTreeViewPrivate::updateScrollBars()
     if (!viewportSize.isValid())
         viewportSize = QSize(0, 0);
 
+    if (viewItems.isEmpty()) {
+        q->doItemsLayout();
+    }
+
     int itemsInViewport = 0;
     if (uniformRowHeights) {
         if (defaultItemHeight <= 0)
diff --git a/src/gui/kernel/qdnd_win.cpp b/src/gui/kernel/qdnd_win.cpp
index a164c2a..7083886 100644
--- a/src/gui/kernel/qdnd_win.cpp
+++ b/src/gui/kernel/qdnd_win.cpp
@@ -515,7 +515,7 @@ static inline Qt::MouseButtons keystate_to_mousebutton(DWORD grfKeyState)
 //---------------------------------------------------------------------
 //                    IDropSource Methods
 //---------------------------------------------------------------------
-STDMETHODIMP
+QT_ENSURE_STACK_ALIGNED_FOR_SSE STDMETHODIMP
 QOleDropSource::QueryContinueDrag(BOOL fEscapePressed, DWORD grfKeyState)
 {
 #ifdef QDND_DEBUG
@@ -545,7 +545,7 @@ QOleDropSource::QueryContinueDrag(BOOL fEscapePressed, DWORD grfKeyState)
     }
 }
 
-STDMETHODIMP
+QT_ENSURE_STACK_ALIGNED_FOR_SSE STDMETHODIMP
 QOleDropSource::GiveFeedback(DWORD dwEffect)
 {
     Qt::DropAction action = translateToQDragDropAction(dwEffect);
@@ -626,7 +626,7 @@ QOleDropTarget::Release(void)
 //                    IDropTarget Methods
 //---------------------------------------------------------------------
 
-STDMETHODIMP
+QT_ENSURE_STACK_ALIGNED_FOR_SSE STDMETHODIMP
 QOleDropTarget::DragEnter(LPDATAOBJECT pDataObj, DWORD grfKeyState, POINTL pt, LPDWORD pdwEffect)
 {
 #ifdef QDND_DEBUG
@@ -688,7 +688,7 @@ void QOleDropTarget::sendDragEnterEvent(QWidget *dragEnterWidget, DWORD grfKeySt
 
 }
 
-STDMETHODIMP
+QT_ENSURE_STACK_ALIGNED_FOR_SSE STDMETHODIMP
 QOleDropTarget::DragOver(DWORD grfKeyState, POINTL pt, LPDWORD pdwEffect)
 {
 #ifdef QDND_DEBUG
@@ -758,7 +758,7 @@ QOleDropTarget::DragOver(DWORD grfKeyState, POINTL pt, LPDWORD pdwEffect)
     return NOERROR;
 }
 
-STDMETHODIMP
+QT_ENSURE_STACK_ALIGNED_FOR_SSE STDMETHODIMP
 QOleDropTarget::DragLeave()
 {
 #ifdef QDND_DEBUG
@@ -785,7 +785,7 @@ QOleDropTarget::DragLeave()
 
 #define KEY_STATE_BUTTON_MASK (MK_LBUTTON | MK_MBUTTON | MK_RBUTTON)
 
-STDMETHODIMP
+QT_ENSURE_STACK_ALIGNED_FOR_SSE STDMETHODIMP
 QOleDropTarget::Drop(LPDATAOBJECT /*pDataObj*/, DWORD grfKeyState, POINTL pt, LPDWORD pdwEffect)
 {
 #ifdef QDND_DEBUG
diff --git a/src/gui/styles/qstylehelper_p.h b/src/gui/styles/qstylehelper_p.h
index 71fce55..3759929 100644
--- a/src/gui/styles/qstylehelper_p.h
+++ b/src/gui/styles/qstylehelper_p.h
@@ -108,7 +108,7 @@ template <typename T>
 {
     typedef HexString<T> type;
     enum { ExactSize = true };
-    static int size(const HexString<T> &str) { return sizeof(str.val) * 2; }
+    static int size(const HexString<T> &) { return sizeof(T) * 2; }
     static inline void appendTo(const HexString<T> &str, QChar *&out) { str.write(out); }
 };
 
diff --git a/src/opengl/gl2paintengineex/qpaintengineex_opengl2.cpp b/src/opengl/gl2paintengineex/qpaintengineex_opengl2.cpp
index 2347e66..6eb5a36 100644
--- a/src/opengl/gl2paintengineex/qpaintengineex_opengl2.cpp
+++ b/src/opengl/gl2paintengineex/qpaintengineex_opengl2.cpp
@@ -866,32 +866,6 @@ void QGL2PaintEngineExPrivate::fill(const QVectorPath& path)
             if (do_vectorpath_cache)
                 path.makeCacheable();
 
-            if (!device->format().stencil()) {
-                // If there is no stencil buffer, triangulate the path instead.
-
-                QRectF bbox = path.controlPointRect();
-                // If the path doesn't fit within these limits, it is possible that the triangulation will fail.
-                bool withinLimits = (bbox.left() > -0x8000 * inverseScale)
-                                  && (bbox.right() < 0x8000 * inverseScale)
-                                  && (bbox.top() > -0x8000 * inverseScale)
-                                  && (bbox.bottom() < 0x8000 * inverseScale);
-                if (withinLimits) {
-                    QTriangleSet polys = qTriangulate(path, QTransform().scale(1 / inverseScale, 1 / inverseScale));
-
-                    QVarLengthArray<float> vertices(polys.vertices.size());
-                    for (int i = 0; i < polys.vertices.size(); ++i)
-                        vertices[i] = float(inverseScale * polys.vertices.at(i));
-
-                    prepareForDraw(currentBrush.isOpaque());
-                    setVertexAttributePointer(QT_VERTEX_COORDS_ATTR, vertices.constData());
-                    glDrawElements(GL_TRIANGLES, polys.indices.size(), GL_UNSIGNED_INT, polys.indices.constData());
-                } else {
-                    // We can't handle big, concave painter paths with OpenGL without stencil buffer.
-                    qWarning("Painter path exceeds +/-32767 pixels.");
-                }
-                return;
-            }
-
             // The path is too complicated & needs the stencil technique
             vertexCoordinateArray.clear();
             vertexCoordinateArray.addPath(path, inverseScale, false);
@@ -1340,7 +1314,7 @@ void QGL2PaintEngineEx::drawPixmap(const QRectF& dest, const QPixmap & pixmap, c
     QGLRect srcRect(src.left(), top, src.right(), bottom);
 
     bool isBitmap = pixmap.isQBitmap();
-    bool isOpaque = !isBitmap && !pixmap.hasAlphaChannel();
+    bool isOpaque = !isBitmap && !pixmap.hasAlphaChannel() && !pixmap.pixmapData()->hasMask();
 
     d->updateTextureFilter(GL_TEXTURE_2D, GL_CLAMP_TO_EDGE,
                            state()->renderHints & QPainter::SmoothPixmapTransform, texture->id);
diff --git a/src/opengl/qgl_x11.cpp b/src/opengl/qgl_x11.cpp
index f3a4c95..7f4c670 100644
--- a/src/opengl/qgl_x11.cpp
+++ b/src/opengl/qgl_x11.cpp
@@ -1776,6 +1776,10 @@ QGLTexture *QGLContextPrivate::bindTextureFromNativePixmap(QPixmap *pixmap, cons
     QX11PixmapData *pixmapData = static_cast<QX11PixmapData*>(pixmap->data_ptr().data());
     Q_ASSERT(pixmapData->classId() == QPixmapData::X11Class);
 
+    // We can't use TFP if the pixmap has a separate X11 mask
+    if (pixmapData->x11_mask)
+        return 0;
+
     if (!qt_resolveTextureFromPixmap(paintDevice))
         return 0;
 
diff --git a/src/opengl/qglframebufferobject.cpp b/src/opengl/qglframebufferobject.cpp
index adbba85..6c9b288 100644
--- a/src/opengl/qglframebufferobject.cpp
+++ b/src/opengl/qglframebufferobject.cpp
@@ -324,10 +324,6 @@ void QGLFBOGLPaintDevice::setFBO(QGLFramebufferObject* f,
         fboFormat.setStencil(true);
     } else if (attachment == QGLFramebufferObject::Depth) {
         fboFormat.setDepth(true);
-        fboFormat.setStencil(false);
-    } else {
-        fboFormat.setDepth(false);
-        fboFormat.setStencil(false);
     }
 
     GLenum format = f->format().internalTextureFormat();
@@ -472,13 +468,17 @@ void QGLFramebufferObjectPrivate::init(QGLFramebufferObject *q, const QSize &sz,
             glGetRenderbufferParameteriv(GL_RENDERBUFFER_EXT, GL_RENDERBUFFER_SAMPLES_EXT, &samples);
     }
 
+    // In practice, a combined depth-stencil buffer is supported by all desktop platforms, while a
+    // separate stencil buffer is not. On embedded devices however, a combined depth-stencil buffer
+    // might not be supported while separate buffers are, according to QTBUG-12861.
+
     if (attachment == QGLFramebufferObject::CombinedDepthStencil
         && (QGLExtensions::glExtensions() & QGLExtensions::PackedDepthStencil)) {
         // depth and stencil buffer needs another extension
-        glGenRenderbuffers(1, &depth_stencil_buffer);
-        Q_ASSERT(!glIsRenderbuffer(depth_stencil_buffer));
-        glBindRenderbuffer(GL_RENDERBUFFER_EXT, depth_stencil_buffer);
-        Q_ASSERT(glIsRenderbuffer(depth_stencil_buffer));
+        glGenRenderbuffers(1, &depth_buffer);
+        Q_ASSERT(!glIsRenderbuffer(depth_buffer));
+        glBindRenderbuffer(GL_RENDERBUFFER_EXT, depth_buffer);
+        Q_ASSERT(glIsRenderbuffer(depth_buffer));
         if (samples != 0 && glRenderbufferStorageMultisampleEXT)
             glRenderbufferStorageMultisampleEXT(GL_RENDERBUFFER_EXT, samples,
                 GL_DEPTH24_STENCIL8_EXT, size.width(), size.height());
@@ -486,24 +486,26 @@ void QGLFramebufferObjectPrivate::init(QGLFramebufferObject *q, const QSize &sz,
             glRenderbufferStorage(GL_RENDERBUFFER_EXT,
                 GL_DEPTH24_STENCIL8_EXT, size.width(), size.height());
 
-        GLint i = 0;
-        glGetRenderbufferParameteriv(GL_RENDERBUFFER_EXT, GL_RENDERBUFFER_DEPTH_SIZE_EXT, &i);
+        stencil_buffer = depth_buffer;
         glFramebufferRenderbuffer(GL_FRAMEBUFFER_EXT, GL_DEPTH_ATTACHMENT_EXT,
-                                     GL_RENDERBUFFER_EXT, depth_stencil_buffer);
+                                     GL_RENDERBUFFER_EXT, depth_buffer);
         glFramebufferRenderbuffer(GL_FRAMEBUFFER_EXT, GL_STENCIL_ATTACHMENT_EXT,
-                                     GL_RENDERBUFFER_EXT, depth_stencil_buffer);
-        fbo_attachment = QGLFramebufferObject::CombinedDepthStencil;
+                                     GL_RENDERBUFFER_EXT, stencil_buffer);
 
         valid = checkFramebufferStatus();
-        if (!valid)
-            glDeleteRenderbuffers(1, &depth_stencil_buffer);
-    } else if (attachment == QGLFramebufferObject::Depth
-               || attachment == QGLFramebufferObject::CombinedDepthStencil)
+        if (!valid) {
+            glDeleteRenderbuffers(1, &depth_buffer);
+            stencil_buffer = depth_buffer = 0;
+        }
+    }
+
+    if (depth_buffer == 0 && (attachment == QGLFramebufferObject::CombinedDepthStencil
+        || (attachment == QGLFramebufferObject::Depth)))
     {
-        glGenRenderbuffers(1, &depth_stencil_buffer);
-        Q_ASSERT(!glIsRenderbuffer(depth_stencil_buffer));
-        glBindRenderbuffer(GL_RENDERBUFFER_EXT, depth_stencil_buffer);
-        Q_ASSERT(glIsRenderbuffer(depth_stencil_buffer));
+        glGenRenderbuffers(1, &depth_buffer);
+        Q_ASSERT(!glIsRenderbuffer(depth_buffer));
+        glBindRenderbuffer(GL_RENDERBUFFER_EXT, depth_buffer);
+        Q_ASSERT(glIsRenderbuffer(depth_buffer));
         if (samples != 0 && glRenderbufferStorageMultisampleEXT) {
 #ifdef QT_OPENGL_ES
 #define GL_DEPTH_COMPONENT16 0x81A5
@@ -521,14 +523,53 @@ void QGLFramebufferObjectPrivate::init(QGLFramebufferObject *q, const QSize &sz,
             glRenderbufferStorage(GL_RENDERBUFFER_EXT, GL_DEPTH_COMPONENT, size.width(), size.height());
 #endif
         }
-        GLint i = 0;
-        glGetRenderbufferParameteriv(GL_RENDERBUFFER_EXT, GL_RENDERBUFFER_DEPTH_SIZE_EXT, &i);
         glFramebufferRenderbuffer(GL_FRAMEBUFFER_EXT, GL_DEPTH_ATTACHMENT_EXT,
-                                     GL_RENDERBUFFER_EXT, depth_stencil_buffer);
-        fbo_attachment = QGLFramebufferObject::Depth;
+                                     GL_RENDERBUFFER_EXT, depth_buffer);
         valid = checkFramebufferStatus();
-        if (!valid)
-            glDeleteRenderbuffers(1, &depth_stencil_buffer);
+        if (!valid) {
+            glDeleteRenderbuffers(1, &depth_buffer);
+            depth_buffer = 0;
+        }
+    }
+
+    if (stencil_buffer == 0 && (attachment == QGLFramebufferObject::CombinedDepthStencil)) {
+        glGenRenderbuffers(1, &stencil_buffer);
+        Q_ASSERT(!glIsRenderbuffer(stencil_buffer));
+        glBindRenderbuffer(GL_RENDERBUFFER_EXT, stencil_buffer);
+        Q_ASSERT(glIsRenderbuffer(stencil_buffer));
+        if (samples != 0 && glRenderbufferStorageMultisampleEXT) {
+#ifdef QT_OPENGL_ES
+            glRenderbufferStorageMultisampleEXT(GL_RENDERBUFFER_EXT, samples,
+                GL_STENCIL_INDEX8_EXT, size.width(), size.height());
+#else
+            glRenderbufferStorageMultisampleEXT(GL_RENDERBUFFER_EXT, samples,
+                GL_STENCIL_INDEX, size.width(), size.height());
+#endif
+        } else {
+#ifdef QT_OPENGL_ES
+            glRenderbufferStorage(GL_RENDERBUFFER_EXT, GL_STENCIL_INDEX8_EXT,
+                                  size.width(), size.height());
+#else
+            glRenderbufferStorage(GL_RENDERBUFFER_EXT, GL_STENCIL_INDEX,
+                                  size.width(), size.height());
+#endif
+        }
+        glFramebufferRenderbuffer(GL_FRAMEBUFFER_EXT, GL_STENCIL_ATTACHMENT_EXT,
+                                  GL_RENDERBUFFER_EXT, stencil_buffer);
+        valid = checkFramebufferStatus();
+        if (!valid) {
+            glDeleteRenderbuffers(1, &stencil_buffer);
+            stencil_buffer = 0;
+        }
+    }
+
+    // The FBO might have become valid after removing the depth or stencil buffer.
+    valid = checkFramebufferStatus();
+
+    if (depth_buffer && stencil_buffer) {
+        fbo_attachment = QGLFramebufferObject::CombinedDepthStencil;
+    } else if (depth_buffer) {
+        fbo_attachment = QGLFramebufferObject::Depth;
     } else {
         fbo_attachment = QGLFramebufferObject::NoAttachment;
     }
@@ -539,6 +580,10 @@ void QGLFramebufferObjectPrivate::init(QGLFramebufferObject *q, const QSize &sz,
             glDeleteRenderbuffers(1, &color_buffer);
         else
             glDeleteTextures(1, &texture);
+        if (depth_buffer)
+            glDeleteRenderbuffers(1, &depth_buffer);
+        if (stencil_buffer && depth_buffer != stencil_buffer)
+            glDeleteRenderbuffers(1, &stencil_buffer);
         glDeleteFramebuffers(1, &fbo);
         fbo_guard.setId(0);
     }
@@ -821,8 +866,10 @@ QGLFramebufferObject::~QGLFramebufferObject()
             glDeleteTextures(1, &d->texture);
         if (d->color_buffer)
             glDeleteRenderbuffers(1, &d->color_buffer);
-        if (d->depth_stencil_buffer)
-            glDeleteRenderbuffers(1, &d->depth_stencil_buffer);
+        if (d->depth_buffer)
+            glDeleteRenderbuffers(1, &d->depth_buffer);
+        if (d->stencil_buffer && d->stencil_buffer != d->depth_buffer)
+            glDeleteRenderbuffers(1, &d->stencil_buffer);
         GLuint fbo = d->fbo();
         glDeleteFramebuffers(1, &fbo);
     }
diff --git a/src/opengl/qglframebufferobject_p.h b/src/opengl/qglframebufferobject_p.h
index d8ff012..58b4e9e 100644
--- a/src/opengl/qglframebufferobject_p.h
+++ b/src/opengl/qglframebufferobject_p.h
@@ -126,7 +126,7 @@ private:
 class QGLFramebufferObjectPrivate
 {
 public:
-    QGLFramebufferObjectPrivate() : fbo_guard(0), texture(0), depth_stencil_buffer(0)
+    QGLFramebufferObjectPrivate() : fbo_guard(0), texture(0), depth_buffer(0), stencil_buffer(0)
                                   , color_buffer(0), valid(false), engine(0) {}
     ~QGLFramebufferObjectPrivate() {}
 
@@ -136,7 +136,8 @@ public:
     bool checkFramebufferStatus() const;
     QGLSharedResourceGuard fbo_guard;
     GLuint texture;
-    GLuint depth_stencil_buffer;
+    GLuint depth_buffer;
+    GLuint stencil_buffer;
     GLuint color_buffer;
     GLenum target;
     QSize size;