abods

function (canvas, container) {
    var history = {state: [], lock: true, mods: 0};

    app.history = history;

    canvas.on('history.lock', function () {
        history.lock = true;
    });
    canvas.on('history.unlock', function () {
        history.lock = false;

abods

// ----------------------------------------------------------
// A short snippet for detecting versions of IE in JavaScript
// without resorting to user-agent sniffing
// ----------------------------------------------------------
// If you're not in IE (or IE version is less than 5) then:
//     ie === undefined
// If you're in IE (>=5) then you can determine which version:
//     ie === 7; // IE7
// Thus, to detect IE:
//     if (ie) {}