Access selected text within a Hotkey object

Access selected text within a Hotkey object

Is it possible to grab user's selected text within Hotkey's scope?
var showHotKey = Hotkey({
combo: "accel-f1",
onPress: function() {
Addon.saveText(window.getSelection().toString());
}
});
Error ..
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());