Add support for modality to QGraphicsItem panels.

This add QGraphicsItem::setPanelModality(), panelModality(),
isBlockedByModalPanel() and the QGraphicsItem::PanelModality enum
(enumerators are either SceneModal, PanelModal, or NonModal, which
mirror Qt::ApplicationModal, Qt::WindowModal, and Qt::NonModal).

Reviewed-by: ahanssen

Squashed commit of the following:

commit a980a1b9c2972c676f3a70e8577d4eace54a25b3
Author: Bradley T. Hughes <bradley.hughes@nokia.com>
Date:   Wed Sep 30 14:42:01 2009 +0200

    Fix tst_QGraphicsItem::modality_hover() test failures

    As pointed out by Andreas, QGraphicsScenePrivate::dispatchHoverEvent()
    already has all the logic needed to correctly dispatch the hover
    events when changing modality. All we need to do is store the last
    known mouse position, and call dispatchHoverEvent() when entering,
    changing, and leaving the modal state.

commit ba41633c96ece8da3a8bbf9c7491c15b14f83f76
Author: Bradley T. Hughes <bradley.hughes@nokia.com>
Date:   Wed Sep 30 14:40:59 2009 +0200

    Fix tst_QGraphicsItem::mixedModality() failure

    When changing modality from SceneModal to PanelModal, we may need to
    send WindowUnblocked events in addition to the WindowBlocked events.

commit d1076e315de10b1b2fb7617ebaee552c14e49c8b
Author: Bradley T. Hughes <bradley.hughes@nokia.com>
Date:   Wed Sep 30 14:33:21 2009 +0200

    Update the expected events counts in tst_QGraphicsItem::modality_hover()

    HoverEnter and HoverMove always come in pairs, and should do so when
    entering or leaving modality as well. This means though that changing
    modality can cause spurious HoverMove events (as seen in this test).

commit a29b098e4c391651ef61dd4714a66b22654e4628
Author: Bradley T. Hughes <bradley.hughes@nokia.com>
Date:   Wed Sep 30 14:20:25 2009 +0200

    Update tst_QGraphicsItem::mixedModality() to do more detailed checking

    The test looks for unwanted WindowBlocked/WindowUnblocked events now,
    making it easier to spot where the failure comes from.

commit c1ae96126ed01d0e662bddf38ff161e50a804b1c
Author: Bradley T. Hughes <bradley.hughes@nokia.com>
Date:   Tue Sep 29 12:17:17 2009 +0200

    Documentation for QGraphicsItem::PanelModality

    Document the behavior of the QGraphicsItem::NonModal, PanelModal, and
    SceneModal enumerators. Corrected a qdoc error in the
    isBlockedByModalPanel() documentation

commit 02fec999e660180ff65bbbf79c8085e582879ed1
Author: Bradley T. Hughes <bradley.hughes@nokia.com>
Date:   Thu Sep 17 10:31:44 2009 +0200

    Add bool QGraphicsItem::isBlockedByModalPanel()

    This function can be used to figure out 1) if an item is modally
    shadowed and 2) which panel is blocking the item in question.

    This will make it possible to implement window-manager like behavior
    of activating/highlighting/animating modal panels when the user tries
    to interact with a blocked item (this will most likely need to be done
    by reimplementing QGraphicsScene::event()).

commit eab9a975dcd71b68135325d479374108bd7f3b2a
Author: Bradley T. Hughes <bradley.hughes@nokia.com>
Date:   Wed Sep 16 14:38:55 2009 +0200

    Block key events to the focus item if it is blocked by a modal panel.

    We don't want the event to propagate either, just stop propagating
    once we reach an item that is blocked.

commit 038b61a10bb837b353f988cb0d1665dd53656cdb
Author: Bradley T. Hughes <bradley.hughes@nokia.com>
Date:   Tue Sep 15 12:40:27 2009 +0200

    Add a test for click-to-focus behavior in the presence of modality

    Clicking on a widget should neither give it focus nor set it as the
    sub-focus item.

commit 3bb3662556efe8d76af5a56e65b1df7a9f4b476a
Author: Bradley T. Hughes <bradley.hughes@nokia.com>
Date:   Tue Sep 8 09:08:42 2009 +0200

    Newly blocked QGraphicsItem panels should lose implicit grabs when
    modality is enabled.

    If an item has an implicit grab when blocked by a modal panel, this grab
    is lost and no mouse events are sent until the mouse is released and re-

commit 3be51be3da36e782a5a1f282c552064d5d490a71
Author: Bradley T. Hughes <bradley.hughes@nokia.com>
Date:   Thu Sep 3 13:39:14 2009 +0200

    Support changing modality from PanelModal to SceneModal or vice-versa

    Don't leave modality first, and then re-enter... this sends
    unnecessary events.

commit bb0aea559ba01a8bbb03c0370a247ab902f561f5
Author: Bradley T. Hughes <bradley.hughes@nokia.com>
Date:   Wed Sep 2 16:58:23 2009 +0200

    Fix hover event delivery in the presence of modal panels

    Panels that are modally shadowed should not get hover events. When
    entering and leaving the modal state, GraphicsSceneHoverEnter and
    GraphicsSceneHoverLeave event should be send to the widgets that
    become or are no longer blocked.

    Auto-test included.

commit cad00b1d9da19565e2d7ea2d30d37eb45005b5ae
Author: Bradley T. Hughes <bradley.hughes@nokia.com>
Date:   Wed Sep 2 10:45:20 2009 +0200

    Fix tst_QGraphicsItem::modality_hover() test

    Don't send hover events to items that are modally shadowed.

commit ae15df331901110e19eb2037f37ff7f84cd7cd16
Author: Bradley T. Hughes <bradley.hughes@nokia.com>
Date:   Wed Sep 2 10:44:14 2009 +0200

    Enable the ItemIsPanel flag in the modality_hover() test

    Otherwise the modality settings are ignored.

commit 1580f43c8feabc3a2bf9c1450e1a8916e8940a4c
Author: Andreas Aardal Hanssen <andreas.aardal.hanssen@nokia.com>
Date:   Fri Aug 28 15:20:37 2009 +0200

    More work on QGraphicsItem::PanelModality. Added many tests.

commit ed2064ad2ec8bc06d62cf1e931b973d5d92c0563
Author: Bradley T. Hughes <bradley.hughes@nokia.com>
Date:   Thu Aug 27 13:45:11 2009 +0200

    Add support for modality to QGraphicsItem panels.

    This add QGraphicsItem::setPanelModality() and the
    QGraphicsItem::PanelModality enum (enumerators are either SceneModal,
    PanelModal, or NonModal, which mirror Qt::ApplicationModal,
    Qt::WindowModal, and Qt::NonModal).

    Reviewed-by: ahanssen

5 files changed, 301 insertions, 21 deletions

diff --git a/src/gui/graphicsview/qgraphicsitem.cpp b/src/gui/graphicsview/qgraphicsitem.cpp
index d7a7bd2..bc9c73f 100644
--- a/src/gui/graphicsview/qgraphicsitem.cpp
+++ b/src/gui/graphicsview/qgraphicsitem.cpp
@@ -564,6 +564,21 @@
     supportsExtension() and setExtension().
 */
 
+/*!
+    \enum QGraphicsItem::PanelModality
+
+    This enum specifies the behavior of a modal panel. A modal panel
+    is one that blocks input to other panels. Note that items that
+    are children of a modal panel are not blocked.
+
+    The values are:
+    \value NonModal   The panel is not modal and does not block input to other panels.
+    \value PanelModal The panel is modal to a single item hierarchy and blocks input to its parent pane, all grandparent panels, and all siblings of its parent and grandparent panels.
+    \value SceneModal The window is modal to the entire scene and blocks input to all panels.
+
+    \sa QGraphicsItem::setPanelModality(), QGraphicsItem::panelModality(), QGraphicsItem::ItemIsPanel
+*/
+
 #include "qgraphicsitem.h"
 
 #ifndef QT_NO_GRAPHICSVIEW
@@ -1649,6 +1664,16 @@ void QGraphicsItem::setFlags(GraphicsItemFlags flags)
         setFlag(ItemStacksBehindParent, d_ptr->z < qreal(0.0));
     }
 
+    if ((d_ptr->panelModality != NonModal)
+        && d_ptr->scene
+        && (flags & ItemIsPanel) != (oldFlags & ItemIsPanel)) {
+        // update the panel's modal state
+        if (flags & ItemIsPanel)
+            d_ptr->scene->d_func()->enterModal(this);
+        else
+            d_ptr->scene->d_func()->leaveModal(this);
+    }
+
     if (d_ptr->scene) {
         d_ptr->scene->d_func()->markDirty(this, QRectF(),
                                           /*invalidateChildren=*/true,
@@ -1725,6 +1750,87 @@ void QGraphicsItem::setCacheMode(CacheMode mode, const QSize &logicalCacheSize)
         update();
 }
 
+/*!
+    \since 4.6
+
+    Returns the modality for this item.
+*/
+QGraphicsItem::PanelModality QGraphicsItem::panelModality() const
+{
+    return d_ptr->panelModality;
+}
+
+/*!
+    \since 4.6
+
+    Sets the modality for this item to \a panelModality.
+
+    Changing the modality of a visible item takes effect immediately.
+*/
+void QGraphicsItem::setPanelModality(PanelModality panelModality)
+{
+    if (d_ptr->panelModality == panelModality)
+        return;
+
+    PanelModality previousModality = d_ptr->panelModality;
+    bool enterLeaveModal = (isPanel() && d_ptr->scene && isVisible());
+    if (enterLeaveModal && panelModality == NonModal)
+        d_ptr->scene->d_func()->leaveModal(this);
+    d_ptr->panelModality = panelModality;
+    if (enterLeaveModal && d_ptr->panelModality != NonModal)
+        d_ptr->scene->d_func()->enterModal(this, previousModality);
+}
+
+/*!
+    \since 4.6
+
+    Returns true if this item is blocked by a modal panel, false otherwise. If \a blockingPanel is
+    non-zero, \a blockingPanel will be set to the modal panel that is blocking this item. If this
+    item is not blocked, \a blockingPanel will not be set by this function.
+
+    This function always returns false for items not in a scene.
+
+    \sa panelModality() setPanelModality() PanelModality
+*/
+bool QGraphicsItem::isBlockedByModalPanel(QGraphicsItem **blockingPanel) const
+{
+    if (!d_ptr->scene)
+        return false;
+
+
+    QGraphicsItem *dummy = 0;
+    if (!blockingPanel)
+        blockingPanel = &dummy;
+
+    QGraphicsScenePrivate *scene_d = d_ptr->scene->d_func();
+    if (scene_d->modalPanels.isEmpty())
+        return false;
+
+    // ###
+    if (!scene_d->popupWidgets.isEmpty() && scene_d->popupWidgets.first() == this)
+        return false;
+
+    for (int i = 0; i < scene_d->modalPanels.count(); ++i) {
+        QGraphicsItem *modalPanel = scene_d->modalPanels.at(i);
+        if (modalPanel->panelModality() == QGraphicsItem::SceneModal) {
+            // Scene modal panels block all non-descendents.
+            if (modalPanel != this && !modalPanel->isAncestorOf(this)) {
+                *blockingPanel = modalPanel;
+                return true;
+            }
+        } else {
+            // Window modal panels block ancestors and siblings/cousins.
+            if (modalPanel != this
+                && !modalPanel->isAncestorOf(this)
+                && commonAncestorItem(modalPanel)) {
+                *blockingPanel = modalPanel;
+                return true;
+            }
+        }
+    }
+    return false;
+}
+
 #ifndef QT_NO_TOOLTIP
 /*!
     Returns the item's tool tip, or an empty QString if no tool tip has been
@@ -1934,6 +2040,8 @@ void QGraphicsItemPrivate::setVisibleHelper(bool newVisible, bool explicitly, bo
                 q->ungrabMouse();
             if (scene->d_func()->keyboardGrabberItems.contains(q))
                 q->ungrabKeyboard();
+            if (q->isPanel() && panelModality != QGraphicsItem::NonModal)
+                scene->d_func()->leaveModal(q_ptr);
         }
         if (q_ptr->hasFocus() && scene) {
             // Hiding the closest non-panel ancestor of the focus item
@@ -1955,10 +2063,15 @@ void QGraphicsItemPrivate::setVisibleHelper(bool newVisible, bool explicitly, bo
     } else {
         geometryChanged = 1;
         paintedViewBoundingRectsNeedRepaint = 1;
-        if (isWidget && scene) {
-            QGraphicsWidget *widget = static_cast<QGraphicsWidget *>(q_ptr);
-            if (widget->windowType() == Qt::Popup)
-                scene->d_func()->addPopup(widget);
+        if (scene) {
+            if (isWidget) {
+                QGraphicsWidget *widget = static_cast<QGraphicsWidget *>(q_ptr);
+                if (widget->windowType() == Qt::Popup)
+                    scene->d_func()->addPopup(widget);
+            }
+            if (q->isPanel() && panelModality != QGraphicsItem::NonModal) {
+                scene->d_func()->enterModal(q_ptr);
+            }
         }
     }
 
@@ -2781,7 +2894,7 @@ bool QGraphicsItem::hasFocus() const
     the preferred focus item for its subtree of items, should it later become
     visible.
 
-    As a result of calling this function, this item will receive a 
+    As a result of calling this function, this item will receive a
     \l{focusInEvent()}{focus in event} with \a focusReason. If another item
     already has focus, that item will first receive a \l{focusOutEvent()}
     {focus out event} indicating that it has lost input focus.
@@ -3299,7 +3412,7 @@ QMatrix QGraphicsItem::matrix() const
 
     The transformation matrix is combined with the item's rotation(), scale()
     and transformations() into a combined transformations for the item.
-    
+
     The default transformation matrix is an identity matrix.
 
     \sa setTransform(), sceneTransform()
@@ -3780,7 +3893,7 @@ void QGraphicsItem::setMatrix(const QMatrix &matrix, bool combine)
 
     // Update and set the new transformation.
     d_ptr->setTransformHelper(newTransform);
-        
+
     // Send post-notification.
     itemChange(ItemTransformHasChanged, qVariantFromValue<QTransform>(newTransform));
 }
@@ -3914,7 +4027,7 @@ void QGraphicsItem::scale(qreal sx, qreal sy)
 /*!
     \obsolete
 
-    Use 
+    Use
 
     \code
     setTransform(QTransform().shear(sh, sv), true);
@@ -3936,7 +4049,7 @@ void QGraphicsItem::shear(qreal sh, qreal sv)
 
     Use setPos() or setTransformOriginPoint() instead. For identical
     behavior, use
-    
+
     \code
     setTransform(QTransform::fromTranslate(dx, dy), true);
     \endcode
@@ -4446,7 +4559,7 @@ bool QGraphicsItem::collidesWithItem(const QGraphicsItem *other, Qt::ItemSelecti
     Note that this function checks whether the item's shape or
     bounding rectangle (depending on \a mode) is contained within \a
     path, and not whether \a path is contained within the items shape
-    or bounding rectangle. 
+    or bounding rectangle.
 
     \sa collidesWithItem(), contains(), shape()
 */
@@ -6595,7 +6708,7 @@ void QGraphicsItem::mousePressEvent(QGraphicsSceneMouseEvent *event)
     if (d_ptr->isWidget) {
         // Qt::Popup closes when you click outside.
         QGraphicsWidget *w = static_cast<QGraphicsWidget *>(this);
-        if (w->windowFlags() & Qt::Popup) {
+        if ((w->windowFlags() & Qt::Popup) == Qt::Popup) {
             event->accept();
             if (!w->rect().contains(event->pos()))
                 w->close();
@@ -7020,7 +7133,7 @@ void QGraphicsItem::prepareGeometryChange()
         // if someone is connected to the changed signal or the scene has no views.
         // Note that this has to be done *after* markDirty to ensure that
         // _q_processDirtyItems is called before _q_emitUpdated.
-	if (scenePrivate->isSignalConnected(scenePrivate->changedSignalIndex)
+        if (scenePrivate->isSignalConnected(scenePrivate->changedSignalIndex)
             || scenePrivate->views.isEmpty()) {
             if (d_ptr->hasTranslateOnlySceneTransform()) {
                 d_ptr->scene->update(boundingRect().translated(d_ptr->sceneTransform.dx(),
@@ -10524,7 +10637,7 @@ QPixmap QGraphicsItemEffectSourcePrivate::pixmap(Qt::CoordinateSystem system, QP
             effectRect.setRight(deviceWidth - 1);
         if (bottom + 1 > deviceHeight)
             effectRect.setBottom(deviceHeight -1);
-        
+
     }
 
     if (effectRect.isEmpty())
diff --git a/src/gui/graphicsview/qgraphicsitem.h b/src/gui/graphicsview/qgraphicsitem.h
index 99d2e12..e6e324a 100644
--- a/src/gui/graphicsview/qgraphicsitem.h
+++ b/src/gui/graphicsview/qgraphicsitem.h
@@ -146,6 +146,13 @@ public:
         DeviceCoordinateCache
     };
 
+    enum PanelModality
+    {
+        NonModal,
+        PanelModal,
+        SceneModal
+    };
+
     QGraphicsItem(QGraphicsItem *parent = 0
 #ifndef Q_QDOC
                   // ### obsolete argument
@@ -183,6 +190,10 @@ public:
     CacheMode cacheMode() const;
     void setCacheMode(CacheMode mode, const QSize &cacheSize = QSize());
 
+    PanelModality panelModality() const;
+    void setPanelModality(PanelModality panelModality);
+    bool isBlockedByModalPanel(QGraphicsItem **blockingPanel = 0) const;
+
 #ifndef QT_NO_TOOLTIP
     QString toolTip() const;
     void setToolTip(const QString &toolTip);
diff --git a/src/gui/graphicsview/qgraphicsitem_p.h b/src/gui/graphicsview/qgraphicsitem_p.h
index 3feccdc..51bfea1 100644
--- a/src/gui/graphicsview/qgraphicsitem_p.h
+++ b/src/gui/graphicsview/qgraphicsitem_p.h
@@ -131,6 +131,7 @@ public:
         subFocusItem(0),
         focusScopeItem(0),
         imHints(Qt::ImhNone),
+        panelModality(QGraphicsItem::NonModal),
         acceptedMouseButtons(0x1f),
         visible(1),
         explicitlyHidden(0),
@@ -448,6 +449,7 @@ public:
     QGraphicsItem *subFocusItem;
     QGraphicsItem *focusScopeItem;
     Qt::InputMethodHints imHints;
+    QGraphicsItem::PanelModality panelModality;
 
     // Packed 32 bits
     quint32 acceptedMouseButtons : 5;
diff --git a/src/gui/graphicsview/qgraphicsscene.cpp b/src/gui/graphicsview/qgraphicsscene.cpp
index 4b74b67..0acef0b 100644
--- a/src/gui/graphicsview/qgraphicsscene.cpp
+++ b/src/gui/graphicsview/qgraphicsscene.cpp
@@ -565,6 +565,9 @@ void QGraphicsScenePrivate::removeItemHelper(QGraphicsItem *item)
             q->removeItem(item->d_ptr->children.at(i));
     }
 
+    if (item->isPanel() && item->isVisible() && item->panelModality() != QGraphicsItem::NonModal)
+        leaveModal(item);
+
     // Reset the mouse grabber and focus item data.
     if (mouseGrabberItems.contains(item))
         ungrabMouse(item, /* item is dying */ item->d_ptr->inDestructor);
@@ -1111,6 +1114,9 @@ void QGraphicsScenePrivate::sendMouseEvent(QGraphicsSceneMouseEvent *mouseEvent)
     }
 
     QGraphicsItem *item = mouseGrabberItems.last();
+    if (item->isBlockedByModalPanel())
+        return;
+
     for (int i = 0x1; i <= 0x10; i <<= 1) {
         Qt::MouseButton button = Qt::MouseButton(i);
         mouseEvent->setButtonDownPos(button, mouseGrabberButtonDownPos.value(button, item->d_ptr->genericMapFromScene(mouseEvent->scenePos(), mouseEvent->widget())));
@@ -1134,6 +1140,8 @@ void QGraphicsScenePrivate::mousePressEventHandler(QGraphicsSceneMouseEvent *mou
 
     // Deliver to any existing mouse grabber.
     if (!mouseGrabberItems.isEmpty()) {
+        if (mouseGrabberItems.last()->isBlockedByModalPanel())
+            return;
         // The event is ignored by default, but we disregard the event's
         // accepted state after delivery; the mouse is grabbed, after all.
         sendMouseEvent(mouseEvent);
@@ -1151,12 +1159,22 @@ void QGraphicsScenePrivate::mousePressEventHandler(QGraphicsSceneMouseEvent *mou
     // Update window activation.
     QGraphicsItem *topItem = cachedItemsUnderMouse.value(0);
     QGraphicsWidget *newActiveWindow = topItem ? topItem->window() : 0;
+    if (newActiveWindow && newActiveWindow->isBlockedByModalPanel(&topItem)) {
+        // pass activation to the blocking modal window
+        newActiveWindow = topItem ? topItem->window() : 0;
+    }
+
     if (newActiveWindow != q->activeWindow())
         q->setActiveWindow(newActiveWindow);
 
     // Set focus on the topmost enabled item that can take focus.
     bool setFocus = false;
     foreach (QGraphicsItem *item, cachedItemsUnderMouse) {
+        if (item->isBlockedByModalPanel()) {
+            // Make sure we don't clear focus.
+            setFocus = true;
+            break;
+        }
         if (item->isEnabled() && ((item->flags() & QGraphicsItem::ItemIsFocusable) && item->d_ptr->mouseSetsFocus)) {
             if (!item->isWidget() || ((QGraphicsWidget *)item)->focusPolicy() & Qt::ClickFocus) {
                 setFocus = true;
@@ -1165,12 +1183,27 @@ void QGraphicsScenePrivate::mousePressEventHandler(QGraphicsSceneMouseEvent *mou
                 break;
             }
         }
+        if (item->isPanel())
+            break;
+    }
+
+    // Check for scene modality.
+    bool sceneModality = false;
+    for (int i = 0; i < modalPanels.size(); ++i) {
+        if (modalPanels.at(i)->panelModality() == QGraphicsItem::SceneModal) {
+            sceneModality = true;
+            break;
+        }
     }
 
     // If nobody could take focus, clear it.
-    if (!stickyFocus && !setFocus)
+    if (!stickyFocus && !setFocus && !sceneModality)
         q->setFocusItem(0, Qt::MouseFocusReason);
 
+    // Any item will do.
+    if (sceneModality && cachedItemsUnderMouse.isEmpty())
+        cachedItemsUnderMouse << modalPanels.first();
+
     // Find a mouse grabber by sending mouse press events to all mouse grabber
     // candidates one at a time, until the event is accepted. It's accepted by
     // default, so the receiver has to explicitly ignore it for it to pass
@@ -1181,6 +1214,10 @@ void QGraphicsScenePrivate::mousePressEventHandler(QGraphicsSceneMouseEvent *mou
             continue;
         }
 
+        // Check if this item is blocked by a modal panel and deliver the mouse event to the
+        // blocking panel instead of this item if blocked.
+        (void) item->isBlockedByModalPanel(&item);
+
         grabMouse(item, /* implicit = */ true);
         mouseEvent->accept();
 
@@ -2403,6 +2440,8 @@ void QGraphicsScene::addItem(QGraphicsItem *item)
         d->selectedItems << item;
     if (item->isWidget() && item->isVisible() && static_cast<QGraphicsWidget *>(item)->windowType() == Qt::Popup)
         d->addPopup(static_cast<QGraphicsWidget *>(item));
+    if (item->isPanel() && item->isVisible() && item->panelModality() != QGraphicsItem::NonModal)
+        d->enterModal(item);
 
     // Update creation order focus chain. Make sure to leave the widget's
     // internal tab order intact.
@@ -3205,8 +3244,12 @@ bool QGraphicsScene::event(QEvent *event)
         }
         return false;
     case QEvent::GraphicsSceneMouseMove:
-        mouseMoveEvent(static_cast<QGraphicsSceneMouseEvent *>(event));
+    {
+        QGraphicsSceneMouseEvent *mouseEvent = static_cast<QGraphicsSceneMouseEvent *>(event);
+        d->lastSceneMousePos = mouseEvent->scenePos();
+        mouseMoveEvent(mouseEvent);
         break;
+    }
     case QEvent::GraphicsSceneMousePress:
         mousePressEvent(static_cast<QGraphicsSceneMouseEvent *>(event));
         break;
@@ -3228,8 +3271,12 @@ bool QGraphicsScene::event(QEvent *event)
     case QEvent::GraphicsSceneHoverEnter:
     case QEvent::GraphicsSceneHoverLeave:
     case QEvent::GraphicsSceneHoverMove:
-        d->dispatchHoverEvent(static_cast<QGraphicsSceneHoverEvent *>(event));
+    {
+        QGraphicsSceneHoverEvent *hoverEvent = static_cast<QGraphicsSceneHoverEvent *>(event);
+        d->lastSceneMousePos = hoverEvent->scenePos();
+        d->dispatchHoverEvent(hoverEvent);
         break;
+    }
     case QEvent::Leave:
         d->leaveScene();
         break;
@@ -3599,8 +3646,10 @@ void QGraphicsScene::helpEvent(QGraphicsSceneHelpEvent *helpEvent)
 
 bool QGraphicsScenePrivate::itemAcceptsHoverEvents_helper(const QGraphicsItem *item) const
 {
-    return item->acceptHoverEvents()
-        || (item->isWidget() && static_cast<const QGraphicsWidget *>(item)->d_func()->hasDecoration());
+    return (!item->isBlockedByModalPanel() &&
+            (item->acceptHoverEvents()
+             || (item->isWidget()
+                 && static_cast<const QGraphicsWidget *>(item)->d_func()->hasDecoration())));
 }
 
 /*!
@@ -3674,7 +3723,9 @@ bool QGraphicsScenePrivate::dispatchHoverEvent(QGraphicsSceneHoverEvent *hoverEv
     }
 
     // Generate a move event for the item itself
-    if (item && !hoverItems.isEmpty() && item == hoverItems.last()) {
+    if (item
+        && !hoverItems.isEmpty()
+        && item == hoverItems.last()) {
         sendHoverEvent(QEvent::GraphicsSceneHoverMove, item, hoverEvent);
         return true;
     }
@@ -3708,8 +3759,7 @@ void QGraphicsScenePrivate::leaveScene()
 
     while (!hoverItems.isEmpty()) {
         QGraphicsItem *lastItem = hoverItems.takeLast();
-        if (lastItem->acceptHoverEvents()
-            || (lastItem->isWidget() && static_cast<QGraphicsWidget*>(lastItem)->d_func()->hasDecoration()))
+        if (itemAcceptsHoverEvents_helper(lastItem))
             sendHoverEvent(QEvent::GraphicsSceneHoverLeave, lastItem, &hoverEvent);
     }
 }
@@ -3736,6 +3786,8 @@ void QGraphicsScene::keyPressEvent(QKeyEvent *keyEvent)
             keyEvent->accept();
             // Send it; QGraphicsItem::keyPressEvent ignores it.  If the event
             // is filtered out, stop propagating it.
+            if (p->isBlockedByModalPanel())
+                break;
             if (!d->sendEvent(p, keyEvent))
                 break;
         } while (!keyEvent->isAccepted() && !p->isPanel() && (p = p->parentItem()));
@@ -3766,6 +3818,8 @@ void QGraphicsScene::keyReleaseEvent(QKeyEvent *keyEvent)
             keyEvent->accept();
             // Send it; QGraphicsItem::keyPressEvent ignores it.  If the event
             // is filtered out, stop propagating it.
+            if (p->isBlockedByModalPanel())
+                break;
             if (!d->sendEvent(p, keyEvent))
                 break;
         } while (!keyEvent->isAccepted() && !p->isPanel() && (p = p->parentItem()));
@@ -5420,6 +5474,8 @@ void QGraphicsScenePrivate::touchEventHandler(QTouchEvent *sceneTouchEvent)
     for (; it != end; ++it) {
         QGraphicsItem *item = it.key();
 
+        (void) item->isBlockedByModalPanel(&item);
+
         // determine event type from the state mask
         QEvent::Type eventType;
         switch (it.value().first) {
@@ -5493,6 +5549,8 @@ bool QGraphicsScenePrivate::sendTouchBeginEvent(QGraphicsItem *origin, QTouchEve
                 break;
             }
         }
+        if (item->isPanel())
+            break;
     }
 
     // If nobody could take focus, clear it.
@@ -5518,6 +5576,8 @@ bool QGraphicsScenePrivate::sendTouchBeginEvent(QGraphicsItem *origin, QTouchEve
             }
             break;
         }
+        if (item->isPanel())
+            break;
     }
 
     touchEvent->setAccepted(eventAccepted);
@@ -5536,6 +5596,94 @@ void QGraphicsScenePrivate::updateInputMethodSensitivityInViews()
         views.at(i)->d_func()->updateInputMethodSensitivity();
 }
 
+void QGraphicsScenePrivate::enterModal(QGraphicsItem *panel, QGraphicsItem::PanelModality previousModality)
+{
+    Q_Q(QGraphicsScene);
+    Q_ASSERT(panel && panel->isPanel());
+
+    QGraphicsItem::PanelModality panelModality = panel->d_ptr->panelModality;
+    if (previousModality != QGraphicsItem::NonModal) {
+        // the panel is changing from one modality type to another... temporarily set it back so
+        // that blockedPanels is populated correctly
+        panel->d_ptr->panelModality = previousModality;
+    }
+
+    QSet<QGraphicsItem *> blockedPanels;
+    QList<QGraphicsItem *> items = q->items(); // ### store panels separately
+    for (int i = 0; i < items.count(); ++i) {
+        QGraphicsItem *item = items.at(i);
+        if (item->isPanel() && item->isBlockedByModalPanel())
+            blockedPanels.insert(item);
+    }
+    // blockedPanels contains all currently blocked panels
+
+    if (previousModality != QGraphicsItem::NonModal) {
+        // reset the modality to the proper value, since we changed it above
+        panel->d_ptr->panelModality = panelModality;
+        // remove this panel so that it will be reinserted at the front of the stack
+        modalPanels.removeAll(panel);
+    }
+
+    modalPanels.prepend(panel);
+
+    if (!hoverItems.isEmpty()) {
+        // send GraphicsSceneHoverLeave events to newly blocked hoverItems
+        QGraphicsSceneHoverEvent hoverEvent;
+        hoverEvent.setScenePos(lastSceneMousePos);
+        dispatchHoverEvent(&hoverEvent);
+    }
+
+    if (!mouseGrabberItems.isEmpty() && lastMouseGrabberItemHasImplicitMouseGrab) {
+        QGraphicsItem *item = mouseGrabberItems.last();
+        if (item->isBlockedByModalPanel())
+            ungrabMouse(item, /*itemIsDying =*/ false);
+    }
+
+    QEvent windowBlockedEvent(QEvent::WindowBlocked);
+    QEvent windowUnblockedEvent(QEvent::WindowUnblocked);
+    for (int i = 0; i < items.count(); ++i) {
+        QGraphicsItem *item = items.at(i);
+        if (item->isPanel()) {
+            if (!blockedPanels.contains(item) && item->isBlockedByModalPanel()) {
+                // send QEvent::WindowBlocked to newly blocked panels
+                sendEvent(item, &windowBlockedEvent);
+            } else if (blockedPanels.contains(item) && !item->isBlockedByModalPanel()) {
+                // send QEvent::WindowUnblocked to unblocked panels when downgrading
+                // a panel from SceneModal to PanelModal
+                sendEvent(item, &windowUnblockedEvent);
+            }
+        }
+    }
+}
+
+void QGraphicsScenePrivate::leaveModal(QGraphicsItem *panel)
+{
+    Q_Q(QGraphicsScene);
+    Q_ASSERT(panel && panel->isPanel());
+
+    QSet<QGraphicsItem *> blockedPanels;
+    QList<QGraphicsItem *> items = q->items(); // ### same as above
+    for (int i = 0; i < items.count(); ++i) {
+        QGraphicsItem *item = items.at(i);
+        if (item->isPanel() && item->isBlockedByModalPanel())
+            blockedPanels.insert(item);
+    }
+
+    modalPanels.removeAll(panel);
+
+    QEvent e(QEvent::WindowUnblocked);
+    for (int i = 0; i < items.count(); ++i) {
+        QGraphicsItem *item = items.at(i);
+        if (item->isPanel() && blockedPanels.contains(item) && !item->isBlockedByModalPanel())
+            sendEvent(item, &e);
+    }
+
+    // send GraphicsSceneHoverEnter events to newly unblocked items
+    QGraphicsSceneHoverEvent hoverEvent;
+    hoverEvent.setScenePos(lastSceneMousePos);
+    dispatchHoverEvent(&hoverEvent);
+}
+
 QT_END_NAMESPACE
 
 #include "moc_qgraphicsscene.cpp"
diff --git a/src/gui/graphicsview/qgraphicsscene_p.h b/src/gui/graphicsview/qgraphicsscene_p.h
index 46917ce..5000860 100644
--- a/src/gui/graphicsview/qgraphicsscene_p.h
+++ b/src/gui/graphicsview/qgraphicsscene_p.h
@@ -160,6 +160,7 @@ public:
     Qt::DropAction lastDropAction;
     QList<QGraphicsItem *> cachedItemsUnderMouse;
     QList<QGraphicsItem *> hoverItems;
+    QPointF lastSceneMousePos;
     bool allItemsIgnoreHoverEvents;
     bool allItemsUseDefaultCursor;
     void enableMouseTrackingOnViews();
@@ -282,6 +283,11 @@ public:
     void enableTouchEventsOnViews();
 
     void updateInputMethodSensitivityInViews();
+
+    QList<QGraphicsItem *> modalPanels;
+    void enterModal(QGraphicsItem *item,
+                    QGraphicsItem::PanelModality panelModality = QGraphicsItem::NonModal);
+    void leaveModal(QGraphicsItem *item);
 };
 
 // QRectF::intersects() returns false always if either the source or target