VTK balloon widget

 #ifndef MAINWINDOW_H

    
 #define MAINWINDOW_H
    
  
    
 #include <QMainWindow>
    
 #include <vtkAutoInit.h>
    
 VTK_MODULE_INIT(vtkRenderingOpenGL2)
    
 VTK_MODULE_INIT(vtkInteractionStyle)
    
 VTK_MODULE_INIT(vtkRenderingFreeType)
    
 #include <vtkSmartPointer.h>
    
 #include <vtkBalloonRepresentation.h>
    
 #include <vtkBalloonWidget.h>
    
 #include <vtkRenderer.h>
    
 #include <vtkRenderWindow.h>
    
 #include <vtkRenderWindowInteractor.h>
    
 #include <vtkSphereSource.h>
    
 #include <vtkRegularPolygonSource.h>
    
 #include <vtkPolyDataMapper.h>
    
 #