Fix DnD when using QSimpleDrag.

qApp->topLevelAt() returns the QShapedPixmapWindow that the DnD
operation created, but what we want is the QWidgetWindow.

QWidgetWindow has the code to handle QDragMove events.

In Qt4, QShapedPixmapWidget had a parent, so was never returned
by qApp->topLevelWidgets().

In Qt5 we must filter it out. Bug is visible in the QNX plugin,
which is the only user of QSimpleDrag.

Change-Id: I920da86f3a1a92ce8e087f5948292fa4c68d4d81
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>

2 files changed, 15 insertions, 3 deletions

diff --git a/src/platformsupport/dnd/qshapedpixmapdndwindow_p.h b/src/platformsupport/dnd/qshapedpixmapdndwindow_p.h
index d377871f99..0448169ec6 100644
--- a/src/platformsupport/dnd/qshapedpixmapdndwindow_p.h
+++ b/src/platformsupport/dnd/qshapedpixmapdndwindow_p.h
@@ -52,6 +52,7 @@ QT_BEGIN_HEADER
 
 class QShapedPixmapWindow : public QWindow
 {
+    Q_OBJECT
 public:
     QShapedPixmapWindow();
 
diff --git a/src/platformsupport/dnd/qsimpledrag.cpp b/src/platformsupport/dnd/qsimpledrag.cpp
index efaede4c5f..13938d6c39 100644
--- a/src/platformsupport/dnd/qsimpledrag.cpp
+++ b/src/platformsupport/dnd/qsimpledrag.cpp
@@ -68,6 +68,17 @@ QT_BEGIN_NAMESPACE
 
 #ifndef QT_NO_DRAGANDDROP
 
+static QWindow* topLevelAt(const QPoint &pos)
+{
+    QWindowList list = QGuiApplication::topLevelWindows();
+    for (int i = list.count()-1; i >= 0; --i) {
+        QWindow *w = list.at(i);
+        if (w->isVisible() && w->geometry().contains(pos) && !qobject_cast<QShapedPixmapWindow*>(w))
+            return w;
+    }
+    return 0;
+}
+
 /*!
     \class QBasicDrag
     \brief QBasicDrag is a base class for implementing platform drag and drop.
@@ -298,7 +309,7 @@ QMimeData *QSimpleDrag::platformDropData()
 void QSimpleDrag::startDrag()
 {
     QBasicDrag::startDrag();
-    m_current_window = QGuiApplication::topLevelAt(QCursor::pos());
+    m_current_window = topLevelAt(QCursor::pos());
     if (m_current_window) {
         QPlatformDragQtResponse response = QWindowSystemInterface::handleDrag(m_current_window, drag()->mimeData(), QCursor::pos(), drag()->supportedActions());
         setCanDrop(response.isAccepted());
@@ -321,7 +332,7 @@ void QSimpleDrag::cancel()
 void QSimpleDrag::move(const QMouseEvent *me)
 {
     QBasicDrag::move(me);
-    QWindow *window = QGuiApplication::topLevelAt(me->globalPos());
+    QWindow *window = topLevelAt(me->globalPos());
     if (!window)
         return;
 
@@ -336,7 +347,7 @@ void QSimpleDrag::move(const QMouseEvent *me)
 void QSimpleDrag::drop(const QMouseEvent *me)
 {
     QBasicDrag::drop(me);
-    QWindow *window = QGuiApplication::topLevelAt(me->globalPos());
+    QWindow *window = topLevelAt(me->globalPos());
     if (!window)
         return;