Implement initial try of wxDropTarget.

The drop target needs to use an event filter to capture drag-and-drop events from the window.

include/wx/qt/window.h

@@ -10,6 +10,7 @@
 #define _WX_QT_WINDOW_H_
 
 #include <list>
+#include <QObject>
 
 class QShortcut;
 template < class T > class QList;
@@ -216,6 +217,16 @@ protected:
     QWidget *m_qtWindow;
 
 private:
+    class DnDEventAdapter : public QObject
+    {
+    public:
+        DnDEventAdapter();
+        virtual bool eventFilter(QObject* watched, QEvent* event);
+        void SetDropTarget(wxDropTarget* dropTarget, QWidget* window);
+    private:
+        wxDropTarget *m_dropTarget;
+    };
+
     void Init();
     QScrollArea *m_qtContainer;
 
@@ -238,6 +249,10 @@ private:
     bool m_processingShortcut;
 #endif // wxUSE_ACCEL
 
+#if wxUSE_DRAG_AND_DROP
+    DnDEventAdapter dnd_event_adapter;
+#endif
+
     wxDECLARE_DYNAMIC_CLASS_NO_COPY( wxWindowQt );
 };