javascript - Hotkey オブジェクト内で選択したテキストにアクセスする

Question

Hotkeyのスコープ内でユーザーが選択したテキストを取得することは可能ですか?
で定義Addon/lib/main.js:

var showHotKey = Hotkey({
    combo: "accel-f1",
    onPress: function() {
        Addon.saveText(window.getSelection().toString());
    }
});

エラー ..

error: Addon: An exception occurred.
ReferenceError: window is not defined
resource://org/Addon/lib/main.js 14
Traceback (most recent call last):
File "resource://gre/modules/commonjs/sdk/keyboard/observer.js", line 39, in handleEvent
    this._emit(event.type, event, event.target.ownerDocument.defaultView);
File "resource://gre/modules/commonjs/sdk/deprecated/events.js", line 123, in _emit
    return this._emitOnObject.apply(this, args);
File "resource://gre/modules/commonjs/sdk/deprecated/events.js", line 153, in _emitOnObject
    listener.apply(targetObj, params);
File "resource://gre/modules/commonjs/sdk/keyboard/hotkeys.js", line 103, in onKeypress
    hotkey();
File "resource://org/Addon/lib/main.js", line 14, in showHotKey<.onPress
    Addon.saveText(window.getSelection().toString());