$(function() {
        // a workaround for a flaw in the demo system (http://dev.jqueryui.com/ticket/4375), ignore!
        // $( "#dialog:ui-dialog" ).dialog( "destroy" );
        
        var name = $( "#name" ),
            email = $( "#email" ),
            phone = $( "#phone" ),
            message = $( "#message" ),
            allFields = $( [] ).add( name ).add( email ).add( phone).add( message ),
            tips = $( ".validateTips" );

        function updateTips( t ) {
            tips
                .text( t )
                .addClass( "ui-state-highlight" );
            setTimeout(function() {
                tips.removeClass( "ui-state-highlight", 1500 );
            }, 500 );
        }

        function checkLength( o, n, min, max ) {
            if ( o.val().length > max || o.val().length < min ) {
                o.addClass( "ui-state-error" );
                updateTips( "Geef voor " + n + " minimaal " + min + " en maximaal " + max + " karakters, a.u.b." );
                return false;
            } else {
                return true;
            }
        }

        function checkRegexp( o, regexp, n ) {
            if ( !( regexp.test( o.val() ) ) ) {
                o.addClass( "ui-state-error" );
                updateTips( n );
                return false;
            } else {
                return true;
            }
        }
        
        $( "#dialog-form" ).dialog({
            autoOpen: false,
            height: 500,
            width: 650,
            modal: true,
            buttons: {
                "Verzenden": function() {
                    var bValid = true;
                    allFields.removeClass( "ui-state-error" );

                    bValid = bValid && checkLength( email, "email", 6, 80 );

                    // From jquery.validate.js (by joern), contributed by Scott Gonzalez: http://projects.scottsplayground.com/email_address_validation/
                    bValid = bValid && checkRegexp( email, /^((([a-z]|\d|[!#\$%&'\*\+\-\/=\?\^_`{\|}~]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])+(\.([a-z]|\d|[!#\$%&'\*\+\-\/=\?\^_`{\|}~]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])+)*)|((\x22)((((\x20|\x09)*(\x0d\x0a))?(\x20|\x09)+)?(([\x01-\x08\x0b\x0c\x0e-\x1f\x7f]|\x21|[\x23-\x5b]|[\x5d-\x7e]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])|(\\([\x01-\x09\x0b\x0c\x0d-\x7f]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF]))))*(((\x20|\x09)*(\x0d\x0a))?(\x20|\x09)+)?(\x22)))@((([a-z]|\d|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])|(([a-z]|\d|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])([a-z]|\d|-|\.|_|~|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])*([a-z]|\d|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])))\.)+(([a-z]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])|(([a-z]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])([a-z]|\d|-|\.|_|~|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])*([a-z]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])))\.?$/i, "eg. ui@jquery.com" );

                    if ( bValid ) {
                        
                        // ajax call here
                        $.ajax({
                          type: "POST",
                          url: "mail.ajax.php",
                          data: { name:name.val(), email:email.val(), phone:phone.val(), message:message.val() },
                        }).done(function( msg ) {
                          alert( "Bericht verstuurd. U ontvangt z.s.m. antwoord van ons.");
                        });
                        
                        
                        $( this ).dialog( "close" );
                    }
                },
                "Annuleren": function() {
                    $( this ).dialog( "close" );
                }
            },
            close: function() {
                allFields.val( "" ).removeClass( "ui-state-error" );
            }
        });

        $( "#mailus, #mailus-footer" )
            .click(function() {
                $( "#dialog-form" ).dialog( "open" );
            });
    });