show only nonconserved residues

Is it possible to show only the nonconserved residues of the sequence alignment with the exception of the reference sequence (mostly the first one)? All conserved residues could than be shown with a special character, typically a dot. Example:

```
ref	GGGGAACTTCTCCTGCTAGAAT
2	GGG...................
3	.................A....
4	...................A..
5	..........T........A..
```