Есть код combotree 
;(function ( $, window, document, undefined ) {
    
    // Create the defaults once
    var comboTreePlugin = 'comboTree',
        defaults = {
            source: [], 
            isMultiple: false
        };

    // The actual plugin constructor
    function ComboTree( element, options ) {
    debugger;
        this.elemInput = element;
        this._elemInput = $(element);

        this.options = $.extend( {}, defaults, options) ;
        
        this._defaults = defaults;
        this._name = comboTreePlugin;
        
        this.init();
    }

    ComboTree.prototype.init = function () {
        // Setting Doms
        this.comboTreeId = 'comboTree' + Math.floor(Math.random() * 999999);

        this._elemInput.addClass('comboTreeInputBox');

        if(this._elemInput.attr('id') === undefined)
            this._elemInput.attr('id', this.comboTreeId + 'Input');
        this.elemInputId = this._elemInput.attr('id');

        this._elemInput.wrap('<div id="'+ this.comboTreeId + 'Wrapper" class="comboTreeWrapper"></div>');
        this._elemInput.wrap('<div id="'+ this.comboTreeId + 'InputWrapper" class="comboTreeInputWrapper"></div>');
        this._elemWrapper = $('#' + this.comboTreeId + 'Wrapper');

        this._elemArrowBtn = $('<button id="' + this.comboTreeId + 'ArrowBtn" class="comboTreeArrowBtn"><span class="comboTreeArrowBtnImg">▼</span></button>');
        this._elemInput.after(this._elemArrowBtn);
        this._elemWrapper.append('<div id="' + this.comboTreeId + 'DropDownContainer" class="comboTreeDropDownContainer"><div class="comboTreeDropDownContent"></div>');
        
        // DORP DOWN AREA
        this._elemDropDownContainer = $('#' + this.comboTreeId + 'DropDownContainer');
        this._elemDropDownContainer.html(this.createSourceHTML());
        
        this._elemItems = this._elemDropDownContainer.find('li');
        this._elemItemsTitle = this._elemDropDownContainer.find('span.comboTreeItemTitle');

        // VARIABLES
        this._selectedItem = {};
        this._selectedItems = [];

        this.bindings();
    };



    // *********************************
    // SOURCES CODES
    // *********************************

    ComboTree.prototype.removeSourceHTML = function () {
        this._elemDropDownContainer.html('');
    };

    ComboTree.prototype.createSourceHTML = function () {
        var htmlText = this.createSourceSubItemsHTML(this.options.source);
        return htmlText;
    };

    ComboTree.prototype.createSourceSubItemsHTML = function (subItems) {
        var subItemsHtml = '<UL>';
        for (var i=0; i<subItems.length; i++){
            subItemsHtml += this.createSourceItemHTML(subItems[i]);
        }
        subItemsHtml += '</UL>'
        return subItemsHtml;
    }

    ComboTree.prototype.createSourceItemHTML = function (sourceItem) {
        var itemHtml = "",
            isThereSubs = sourceItem.hasOwnProperty("subs");
        
        itemHtml = '<LI class="ComboTreeItem' + (isThereSubs?'Parent':'Chlid') + '"> ';
        
        if (isThereSubs)
            itemHtml += '<span class="comboTreeParentPlus">&minus;</span>';

        if (this.options.isMultiple)
            itemHtml += '<span data-id="' + sourceItem.id + '" class="comboTreeItemTitle"><input type="checkbox">' + sourceItem.title + '</span>';
        else
            itemHtml += '<span data-id="' + sourceItem.id + '" class="comboTreeItemTitle">' + sourceItem.title + '</span>';

        if (isThereSubs)
            itemHtml += this.createSourceSubItemsHTML(sourceItem.subs);

        itemHtml += '</LI>';
        return itemHtml;
    };


    // BINDINGS
    // *****************************
    ComboTree.prototype.bindings = function () {
        var _this = this;

        this._elemArrowBtn.on('click', function(e){
            e.stopPropagation();
            _this.toggleDropDown();
        });
        this._elemInput.on('click', function(e){
            e.stopPropagation();
            if (!_this._elemDropDownContainer.is(':visible'))
                _this.toggleDropDown();
        });
        this._elemItems.on('click', function(e){
            e.stopPropagation();
            if ($(this).hasClass('ComboTreeItemParent')){
                _this.toggleSelectionTree(this);
            }
        });        
        this._elemItemsTitle.on('click', function(e){
            e.stopPropagation();
            if (_this.options.isMultiple)
                _this.multiItemClick(this);
            else
                _this.singleItemClick(this);
        });
        this._elemItemsTitle.on("mousemove", function (e) {
            e.stopPropagation();
            _this.dropDownMenuHover(this);
        });

        // KEY BINDINGS
        this._elemInput.on('keyup', function(e) {
            e.stopPropagation();

            switch (e.keyCode) {
                case 27:
                    _this.closeDropDownMenu(); break;
                case 13:                  
                case 39: case 37: case 40: case 38:
                    e.preventDefault(); 
                    break;
                default: 
                    if (!_this.options.isMultiple)
                        _this.filterDropDownMenu(); 
                    break;
            }
        });
        this._elemInput.on('keydown', function(e) {
            e.stopPropagation();

            switch (e.keyCode) {
            case 9:
                _this.closeDropDownMenu(); break;
            case 40: case 38:
                e.preventDefault(); 
                _this.dropDownInputKeyControl(e.keyCode - 39); break;
            case 37: case 39:
                e.preventDefault(); 
                _this.dropDownInputKeyToggleTreeControl(e.keyCode - 38);
                break;
            case 13:
                if (_this.options.isMultiple)
                    _this.multiItemClick(_this._elemHoveredItem);
                else
                    _this.singleItemClick(_this._elemHoveredItem);
                e.preventDefault(); 
                break;
            default: 
                if (_this.options.isMultiple)
                    e.preventDefault();
        }
        });
        // ON FOCUS OUT CLOSE DROPDOWN
        $(document).on('mouseup.' + _this.comboTreeId, function (e){
            if (!_this._elemWrapper.is(e.target) && _this._elemWrapper.has(e.target).length === 0 && _this._elemDropDownContainer.is(':visible'))
                _this.closeDropDownMenu();
        });
    };




    // EVENTS HERE 
    // ****************************

    // DropDown Menu Open/Close
    ComboTree.prototype.toggleDropDown = function () {
        this._elemDropDownContainer.slideToggle(50);
        this._elemInput.focus();
    };
    ComboTree.prototype.closeDropDownMenu = function () {
        this._elemDropDownContainer.slideUp(50);
    };
    // Selection Tree Open/Close
    ComboTree.prototype.toggleSelectionTree = function (item, direction) {
        var subMenu = $(item).children('ul')[0];
        if (direction === undefined){
            if ($(subMenu).is(':visible'))
                $(item).children('span.comboTreeParentPlus').html("+");
            else
                $(item).children('span.comboTreeParentPlus').html("&minus;");

            $(subMenu).slideToggle(50);
        }
        else if (direction == 1 && !$(subMenu).is(':visible')){
                $(item).children('span.comboTreeParentPlus').html("&minus;");
                $(subMenu).slideDown(50);
        }
        else if (direction == -1){
            if ($(subMenu).is(':visible')){
                $(item).children('span.comboTreeParentPlus').html("+");
                $(subMenu).slideUp(50);
            }
            else {
                this.dropDownMenuHoverToParentItem(item);
            }
        }
            
    };


    // SELECTION FUNCTIONS
    // *****************************
    ComboTree.prototype.singleItemClick = function (ctItem) {
        this._selectedItem = {
            id: $(ctItem).attr("data-id"),
            title: $(ctItem).text()
        };

        this.refreshInputVal();
        this.closeDropDownMenu();
    };
    ComboTree.prototype.multiItemClick = function (ctItem) {
        this._selectedItem = {
            id: $(ctItem).attr("data-id"),
            title: $(ctItem).text()
        };

        var index = this.isItemInArray(this._selectedItem, this._selectedItems);
        if (index){
            this._selectedItems.splice(parseInt(index), 1);
            $(ctItem).find("input").prop('checked', false);
        }
        else {
            this._selectedItems.push(this._selectedItem);
            $(ctItem).find("input").prop('checked', true);
        }

        this.refreshInputVal();
    };

    ComboTree.prototype.isItemInArray = function (item, arr) {

        for (var i=0; i<arr.length; i++)
            if (item.id == arr[i].id && item.title == arr[i].title)
                return i + "";

        return false;
    }

    ComboTree.prototype.refreshInputVal = function () {
        var tmpTitle = "";
        
        if (this.options.isMultiple) {
            for (var i=0; i<this._selectedItems.length; i++){
                tmpTitle += this._selectedItems[i].title;
                if (i<this._selectedItems.length-1)
                    tmpTitle += ", ";
            }
        }
        else {
            tmpTitle = this._selectedItem.title;
        }

        this._elemInput.val(tmpTitle);
    }

    ComboTree.prototype.dropDownMenuHover = function (itemSpan, withScroll) {
        this._elemItems.find('span.comboTreeItemHover').removeClass('comboTreeItemHover');
        $(itemSpan).addClass('comboTreeItemHover');
        this._elemHoveredItem = $(itemSpan);
        if (withScroll)
            this.dropDownScrollToHoveredItem(this._elemHoveredItem);
    }

    ComboTree.prototype.dropDownScrollToHoveredItem = function (itemSpan) {
        var curScroll = this._elemDropDownContainer.scrollTop();
        this._elemDropDownContainer.scrollTop(curScroll + $(itemSpan).parent().position().top - 80);
    }

    ComboTree.prototype.dropDownMenuHoverToParentItem = function (item) {
        var parentSpanItem = $($(item).parents('li.ComboTreeItemParent')[0]).children("span.comboTreeItemTitle");
        if (parentSpanItem.length)
            this.dropDownMenuHover(parentSpanItem, true);
        else 
            this.dropDownMenuHover(this._elemItemsTitle[0], true);
    }

    ComboTree.prototype.dropDownInputKeyToggleTreeControl = function (direction) {
        var item = this._elemHoveredItem;
        if ($(item).parent('li').hasClass('ComboTreeItemParent'))
            this.toggleSelectionTree($(item).parent('li'), direction);
        else if (direction == -1)
            this.dropDownMenuHoverToParentItem(item);
    }

    ComboTree.prototype.dropDownInputKeyControl = function (step) {
        if (!this._elemDropDownContainer.is(":visible")) 
            this.toggleDropDown();

        var list = this._elemItems.find("span.comboTreeItemTitle:visible");
        i = this._elemHoveredItem?list.index(this._elemHoveredItem) + step:0;
        i = (list.length + i) % list.length;

        this.dropDownMenuHover(list[i], true);        
    },

    ComboTree.prototype.filterDropDownMenu = function () {
        var searchText = this._elemInput.val();
        if (searchText != ""){
            this._elemItemsTitle.hide();
            this._elemItemsTitle.siblings("span.comboTreeParentPlus").hide();
            list = this._elemItems.find("span:icontains('" + this._elemInput.val() + "')").each(function (i, elem) {
                $(this).show();
                $(this).siblings("span.comboTreeParentPlus").show();
            });    
        }
        else{
            this._elemItemsTitle.show();
            this._elemItemsTitle.siblings("span.comboTreeParentPlus").show();
        }
    }

    // Retuns Array (multiple), Integer (single), or False (No choice)
    ComboTree.prototype.getSelectedItemsId = function () {
        if (this.options.isMultiple && this._selectedItems.length>0){
            var tmpArr = [];
            for (i=0; i<this._selectedItems.length; i++)
                tmpArr.push(this._selectedItems[i].id);

            return tmpArr;
        }
        else if (!this.options.isMultiple && this._selectedItem.hasOwnProperty('id')){
            return this._selectedItem.id;
        }
        return false;
    }

    // Retuns Array (multiple), Integer (single), or False (No choice)
    ComboTree.prototype.getSelectedItemsTitle = function () {
        if (this.options.isMultiple && this._selectedItems.length>0){
            var tmpArr = [];
            for (i=0; i<this._selectedItems.length; i++)
                tmpArr.push(this._selectedItems[i].title);

            return tmpArr;
        }
        else if (!this.options.isMultiple && this._selectedItem.hasOwnProperty('id')){
            return this._selectedItem.title;
        }
        return false;
    }


    ComboTree.prototype.unbind = function () {
        this._elemArrowBtn.off('click');
        this._elemInput.off('click');
        this._elemItems.off('click');        
        this._elemItemsTitle.off('click');
        this._elemItemsTitle.off("mousemove");
        this._elemInput.off('keyup');
        this._elemInput.off('keydown');
        this._elemInput.off('mouseup.' + this.comboTreeId);
        $(document).off('mouseup.' + this.comboTreeId);
    }

    ComboTree.prototype.destroy = function () {
        this.unbind();
        this._elemWrapper.before(this._elemInput);
        this._elemWrapper.remove();
        this._elemInput.removeData('plugin_' + comboTreePlugin);
    }


    $.fn[comboTreePlugin] = function ( options) {
        var ctArr = [];
        this.each(function () {
            if (!$.data(this, 'plugin_' + comboTreePlugin)) {
               $.data(this, 'plugin_' + comboTreePlugin, new ComboTree( this, options));
               ctArr.push($(this).data()['plugin_' + comboTreePlugin]);
            }
        });

        if (this.length == 1)
            return ctArr[0];
        else
            return ctArr;
    }

})( jQuery, window, document );


var SampleJSONData = [
{
    id: 0,
    title: 'choice 1  '
}, {
    id: 1,
    title: 'choice 2',
    subs: [
        {
            id: 10,
            title: 'choice 2 1'
        }, {
            id: 11,
            title: 'choice 2 2'
        }, {
            id: 12,
            title: 'choice 2 3'
        }
    ]
}, {
    id: 2,
    title: 'choice 3'
}, {
    id: 3,
    title: 'choice 4'
}, {
    id: 4,
    title: 'choice 5'
}, {
    id: 5,
    title: 'choice 6',
    subs: [
        {
            id: 50,
            title: 'choice 6 1'
        }, {
            id: 51,
            title: 'choice 6 2',
            subs: [
                {
                    id: 510,
                    title: 'choice 6 2 1'
                }, {
                    id: 511,
                    title: 'choice 6 2 2'
                }, {
                    id: 512,
                    title: 'choice 6 2 3'
                }
            ]
        }
    ]
}, {
    id: 6,
    title: 'choice 7'
}
];


var comboTree1 = $('#example').comboTree({
	source : SampleJSONData,
	isMultiple: false
});
Мне нужно поменять его таким образом, чтобы при поднесении к какому нибудь элементу мыши (hover) он сразу открывался