Outline on selection in SOM

```
Currently, to highlight selected nodes of an SOM, a semi-transparent white mask 
is put over those nodes. It can still be hard to see what was selected, so on 
top of this there should be an outline around the border of the selected area 
as well.
```

Original issue reported on code.google.com by `kyle.tha...@gmail.com` on 15 Apr 2011 at 4:26
