QGraphicsView: Handle wheelEvents correctly with Qt::Popup widgets.

This fixes an issue in QtWebKit where scrolling with the wheel while
a combo box is opened cause the page to scroll while the popup don't
move. This patch either ignore the event on Mac or close the popup on
other platforms.

Reviewed-by: Yoann Lopes

1 files changed, 19 insertions, 0 deletions

diff --git a/src/gui/graphicsview/qgraphicsscene.cpp b/src/gui/graphicsview/qgraphicsscene.cpp
index b821551..e5264da 100644
--- a/src/gui/graphicsview/qgraphicsscene.cpp
+++ b/src/gui/graphicsview/qgraphicsscene.cpp
@@ -4162,6 +4162,25 @@ void QGraphicsScene::wheelEvent(QGraphicsSceneWheelEvent *wheelEvent)
                                                                 wheelEvent->scenePos(),
                                                                 wheelEvent->widget());
 
+#ifdef Q_WS_MAC
+    // On Mac, ignore the event if the first item under the mouse is not the last opened
+    // popup (or one of its descendant)
+    if (!d->popupWidgets.isEmpty() && !wheelCandidates.isEmpty() && wheelCandidates.first() != d->popupWidgets.back() && !d->popupWidgets.back()->isAncestorOf(wheelCandidates.first())) {
+        wheelEvent->accept();
+        return;
+    }
+#else
+    // Find the first popup under the mouse (including the popup's descendants) starting from the last.
+    // Remove all popups after the one found, or all or them if no popup is under the mouse.
+    // Then continue with the event.
+    QList<QGraphicsWidget *>::const_iterator iter = d->popupWidgets.end();
+    while (--iter >= d->popupWidgets.begin() && !wheelCandidates.isEmpty()) {
+        if (wheelCandidates.first() == *iter || (*iter)->isAncestorOf(wheelCandidates.first()))
+            break;
+        d->removePopup(*iter);
+    }
+#endif
+
     bool hasSetFocus = false;
     foreach (QGraphicsItem *item, wheelCandidates) {
         if (!hasSetFocus && item->isEnabled()