public function nestedform(HTTPRequest $r)
    {
        $req = new BetterButtonsNestedFormRequest($this, $this->owner, $this->owner->ItemEditForm());

        return $req->handleRequest($r, DataModel::inst());
    }
public function nestedform(HTTPRequest $r)
    {
        $req = new BetterButtonsNestedFormRequest($this, $this->owner, $this->owner->ItemEditForm());

        return $req->handleRequest($r, DataModel::inst());
    }
Handles all custom action from DataObjects and hands them off to a sub-controller.
e.g. /nestedform?action=myDataObjectAction

@param  HTTPRequest $r
@return BetterButtonsNestedFormRequest