def text_callback(obj, event):
    global rulez
    print('Text selected')
    if rulez:
        obj.GetTextActor().SetInput('Diffusion Imaging Rulez!!')
        rulez = False
    else:
        obj.GetTextActor().SetInput('Diffusion Imaging in Python')
        rulez = True
    show_manager.render()
def text_callback(obj, event):
    global rulez
    print('Text selected')
    if rulez:
        obj.GetTextActor().SetInput('Diffusion Imaging Rulez!!')
        rulez = False
    else:
        obj.GetTextActor().SetInput('Diffusion Imaging in Python')
        rulez = True
    show_manager.render()