The underlying object controls the way of sorting. Like Serpet Consulting said, using the "_order" parameter on that object you can define a field on which to sort. You can also define if that should be descending or ascending.

For example, the field value_ids would point to record of the object my.values, then your code should look like so:

class myvalue(osv.osv):

    _name = "my.values"

    _order = "myfield asc"

Note by the way that his does not fix/add any kind of tree view. It is just the same records list without indentation but only sorted on a different field. 

[EDIT]

About hiding items in a list: Hiding in a list is done using a domain. For example, suppose you want all the elements of my.value where the field "myinteger" is higher than 4. You would create a construction like:

"my_value_ids" : fields.one2many("my.value", string="My values", domain="[("myinteger",">",4)]"),

you can also define a domain on the XML view of the other object referencing to my.value, like so:

<field name="my_value_ids"  domain="[('myinteger','>',4)]"/>