Ti.UI.TextArea.keyboardToolbar is not displayed at modal window. (Titanium Mobile 1.6 / iOS SDK 4.2)

app.js

var window = Ti.UI.createWindow({
	modal: true,	// If this line is deleted, keyboardToolbar is displayed. 
	title: 'window',
	backgroundColor: '#fff'
});
var trash = Ti.UI.createButton({
	systemButton: Ti.UI.iPhone.SystemButton.TRASH
});
var textarea = Ti.UI.createTextArea({
	editable: true,
	borderWidth: 1,
	keyboardToolbar: [trash]
});
window.add(textarea);
window.addEventListener('open', function () {
	textarea.focus();
});
window.open();