how to update VTKDataSource data in Mayavi 4.4.3

Hi,

I have a custom mini-traits-UI app written on top of mayavi, that plots unstructured mesh and some data on the mesh into a mayavi scene. It supports plotting several "time steps", and when a time step is changed (e.g. using a slder in the GUI), new data corresponding to the same mesh are loaded, and an existing `mayavi.sources.vtk_data_source.VTKDataSource` called `vis_source` is updated as follows:

```
vis_source.data = new_data
```

Prior to Mayavi version 4.4, this lead to the update of the pipeline depending on the source, and the visible scene updated. With 4.4, the visible scene does not update - the old data are still displayed. What can I do to fix this?

Thanks,
r.