fix: GUI Disappearing #1522 (Mac OSX)

- this solution works stable on mac and ensures that the window get's reopened when the user clicks the dock icon .
- tested on 10.8 with Qt4.8.4 and Qt5.0.1

Signed-off-by: Jonas Schnelli <jonas.schnelli@include7.ch>

src/qt/macdockiconhandler.h

@@ -2,6 +2,7 @@
 #define MACDOCKICONHANDLER_H
 
 #include <QObject>
+#include <QMainWindow>
 
 QT_BEGIN_NAMESPACE
 class QMenu;
@@ -26,7 +27,7 @@ public:
 
     QMenu *dockMenu();
     void setIcon(const QIcon &icon);
-
+    void setMainWindow(QMainWindow *window);
     static MacDockIconHandler *instance();
 
     void handleDockIconClickEvent();
@@ -40,6 +41,7 @@ private:
     DockIconClickEventHandler *m_dockIconClickEventHandler;
     QWidget *m_dummyWidget;
     QMenu *m_dockMenu;
+    QMainWindow *mainWindow;
 };
 
 #endif // MACDOCKICONCLICKHANDLER_H