$(function(){
    $("#but_login").click(function(){
        var user = $("#txt_user").val();
        var pass = $("#txt_pass").val();
        if(user == '' || pass == '')
        {
            alert("Existem campos em branco!");
            return false;
        }
        else
        {
            $("#form_login").hide("slow");
            beforeSend:$("#carregando_form").show('normal');

            $.post(
                "login.php",
                { user:user, pass:pass },
                function( data )
                {
                    alert( data+' '+typeof( data ) );

                    if ( data == 'loginaceito')
                    {
                        alert( 'entrou no if' );
                        $('#retorno').show("slow").html('Teste - Login Ok');
                    }
                    else
                    {
                        alert( 'entrou no else' );
                        $('#form_login').show("slow");
                        $('#form_login > .erro').text(login)
                        $('.ui-tabs-disabled').removeClass('ui-tabs-disabled');
                    }
                }
            );
        }
    });
});