Q:

How do I get backbone to bind the submit event to a form? 

I'm using the following code to create the view:
LoginForm = Backbone.View.extend({

    tagName :"form"
    ,id : "login-form"
    ,className :"navbar-form"
    ,initialize: function () {
            this.model = new StackMob. User();
            this.render();
    }
    ,render: function () {
            $(this.el).html(this.template());
            return this;
    }
    ,events : {
            "change" : "change"
            ,"submit #login-form" : "login"
    }
    ,login : function( event) {
            event.preventDefault();
            var self = this;
            this.model.login(true, {
                    success: function( model) {
                            app.alertSuccess( "User logged in");
                            self.render();
                    }
                    ,error: function( model, response) {
                            app.alertError("Could not login  user: " + response.error_description);
                    }
            });
            event.currentTarget.checkValidity();
            return false;
    }
// rest of code

And the template:
<input name="username" class="span2" type="email" placeholder="Email" required >
<input name="password" class="span2" type="password" placeholder="Password" required >
<button id="login-button" type="submit" class="btn">Sign in</button>

When I bind on the button, the login function gets called.   Binding on the form submit event, the login function does not get called.   I can also get the form to bind if the id & form tag are part of the template, which is not what I want to do here. 
How do I bind on the form submit in this case? 

A:

"submit #login-form" : "login"

I think Backbone will search for this id among the descendants only.  So it will never match your own view element.  Why don't you just use:
"submit": "login"

As you did for change. 
Gonna check Backbone's code just to be sure. 
Edit:
If you put a selector, Backbone will call
this.$el.on(event, selector, method);

instead of
this.$el.on(event, method);

And the on method of jQuery will instead apply the selector to the descendants of the element only, excluding the element itself. 

A:

You're using Backbone wrong.  So what you're going to want to do,
template: my_template_string,
render: function () {
    this.el.innerHTML = this.template();
},
events: {
    "submit #login-form": function (event) {}
}

Where this.template is set to
<form id="login-form" class="navbar-form">
    <input name="username" class="span2" type="email" placeholder="Email" required >
    <input name="password" class="span2" type="password" placeholder="Password" required >
    <button id="login-button" type="submit" class="btn">Sign in</button>
</form>

And doesn't that only make sense?  Why would you want the id and classname to be separated from the input elements?  BTW, you can still do the naked catchall on submit, but only in my method will,

the <form> class, and <form> attribute be tied to the form's template, and not just the backbone view,
will you be explicitly capturing the right submit,
can you ever support multiple submit events (in the event one template has two forms).