Add new signal on the mainWindow

We can't just call things on the mainWindow, we need to
wait it to finish some processes before we can safely query things

src/gui/mainwindow.cpp

@@ -756,6 +756,7 @@ void MainWindow::on_m_DeviceScanner_finished()
 
     updateSeletedDeviceMenu();
     checkFileSystemSupport();
+    Q_EMIT scanFinished();
 }
 
 void MainWindow::updateSeletedDeviceMenu()

src/gui/mainwindow.h

@@ -46,6 +46,7 @@ public:
 
 Q_SIGNALS:
     void settingsChanged();
+    void scanFinished();
 
 protected:
     void init();