Ox.OptionGroup = function(items, min, max, property) {

    /*
        to be used by ButtonGroup, CheckboxGroup, Select and Menu
    */

    var property = property || 'checked'
        length = items.length,
        max = max == -1 ? length : max;

    function getLastBefore(pos) {
        // returns the position of the last checked item before position pos
        var last = -1;
        /*Ox.print(items, items.length, length, $.merge(
            pos > 0 ? Ox.range(pos - 1, -1, -1) : [],
            pos < items.length - 1 ? Ox.range(items.length - 1, pos, -1) : []
        ))*/
        // fixme: why is length not == items.length here?
        Ox.forEach($.merge(
            pos > 0 ? Ox.range(pos - 1, -1, -1) : [],
            pos < items.length - 1 ? Ox.range(items.length - 1, pos, -1) : []
        ), function(v) {
            //Ox.print(pos, v)
            if (items[v][property]) {
                last = v;
                return false;
            }
        });
        return last;
    }

    function getNumber() {
        // returns the number of checked items
        var num = 0;
        items.forEach(function(item) {
            if (item[property]) {
                num++;
            }
        })
        return num;
    }

    this[property] = function() {
        // returns an array with the positions of all checked item
        var checked = [];
        items.forEach(function(item, i) {
            if (item[property]) {
                checked.push(i);
            }
        })
        return checked;
    };

    this.init = function() {
        var num = getNumber(),
            count = 0;
        //if (num < min || num > max) {
            items.forEach(function(item) {
                if (Ox.isUndefined(item[property])) {
                    item[property] = false;
                }
                if (item[property]) {
                    count++;
                    if (count > max) {
                        item[property] = false;
                    }
                } else {
                    if (num < min) {
                        item[property] = true;
                        num++;
                    }
                }
            });
        //}
        return items;
    };

    this.toggle = function(pos) {
        var last,
            num = getNumber(),
            toggled = [];
        if (!items[pos][property]) { // check
            if (num >= max) {
                last = getLastBefore(pos);
                items[last][property] = false;
                toggled.push(last);
            }
            if (!items[pos][property]) {
                items[pos][property] = true;
                toggled.push(pos);
            }
        } else { // uncheck
            if (num > min) {
                items[pos][property] = false;
                toggled.push(pos);
            }
        }
        return toggled;
    }

    return this;

}