//when key is pressed in the textbox
$(document).ready(function() {

    $("#left_middle :text").keypress(function(e) {
        if ((e.which && e.which == 13) || (e.keyCode && e.keyCode == 13)) {
            e.preventDefault();
            var button = $("#left_middle :submit").eq(0);
            if (button) {
                button.click();
            }
        }
    });

    $(":text,:password").not("#left_middle :text").keypress(function(e) {
        if ((e.which && e.which == 13) || (e.keyCode && e.keyCode == 13)) {
            e.preventDefault();
            var button = $('.default_button').eq(0);
            if (button) {
                button.click();
            }
        }
    });
});