src/js/theme/toolbar.js
function createDropdownMenu(dropdown) {
    var $menu = $('<div>', {
        'class': 'dropdown-menu',
        'html': '<div class="dropdown-caret"><span class="caret-outer"></span><span class="caret-inner"></span></div>'
    });

    if (typeof dropdown == 'string') {
        $menu.append(dropdown);
    } else {
        var groups = dropdown.map(function(group) {
            if ($.isArray(group)) return group;
            else return [group];
        });

        // Create buttons groups
        groups.forEach(function(group) {
            var $group = $('<div>', {
                'class': 'buttons'
            });
            var sizeClass = 'size-'+group.length;

            // Append buttons
            group.forEach(function(btn) {
                btn = $.extend({
                    text: '',
                    className: '',
                    onClick: defaultOnClick
                }, btn || {});

                var $btn = $('<button>', {
                    'class': 'button '+sizeClass+' '+btn.className,
                    'text': btn.text
                });
                $btn.click(btn.onClick);

                $group.append($btn);
            });


            $menu.append($group);
        });

    }


    return $menu;
}
function createDropdownMenu(dropdown) {
    var $menu = $('<div>', {
        'class': 'dropdown-menu',
        'html': '<div class="dropdown-caret"><span class="caret-outer"></span><span class="caret-inner"></span></div>'
    });

    if (typeof dropdown == 'string') {
        $menu.append(dropdown);
    } else {
        var groups = dropdown.map(function(group) {
            if ($.isArray(group)) return group;
            else return [group];
        });

        // Create buttons groups
        groups.forEach(function(group) {
            var $group = $('<div>', {
                'class': 'buttons'
            });
            var sizeClass = 'size-'+group.length;

            // Append buttons
            group.forEach(function(btn) {
                btn = $.extend({
                    text: '',
                    className: '',
                    onClick: defaultOnClick
                }, btn || {});

                var $btn = $('<button>', {
                    'class': 'button '+sizeClass+' '+btn.className,
                    'text': btn.text
                });
                $btn.click(btn.onClick);

                $group.append($btn);
            });


            $menu.append($group);
        });

    }


    return $menu;
}
Create a dropdown menu