"event is not defined" when right click.

[Likey]

I use v2.1.1

When I right click on <canvas> of game, I get a message from Firefox console:

ReferenceError: event is not defined

The line 253 ~ 263 of CCApplication.js is:

cc.setContextMenuEnable = function (enabled) {
    cc._isContextMenuEnable = enabled;
    if (!cc._isContextMenuEnable) {
        cc.canvas.oncontextmenu = function () {
            event.returnValue = false;
        };
    } else {
        cc.canvas.oncontextmenu = function () {
        };
    }
};

The problem is at line 257:

event.returnValue = false;

I think that the code is to prevent contextmenu on right click.
Is it better to replace line 257 with following:

return false;

[dingpinglv]

Thank you, Chen.
I will fix this issue soon.