In pre-V7, it was possible for users to switch one2many fields views using small icons on top like those of the main view. I do not know how to get this functionality in v7.
I noted that many views include both
<form> in the
<field> tag. Sale order line uses either tree or form view based in group, but in most other object, the form view is not used at all. Is it possible to allow users to edit using the form view through the web interface, possibly with an action button.