Expanding tree is not stable on windows

Expanding tree in windows is not stable. Sometimes there are no subnodes even though there should be some.
![org jboss reddeer swt test menutest-menuwithmnemonictest](https://f.cloud.github.com/assets/1215011/2472798/74beb1b4-b03a-11e3-8932-3c2aeb0a7ad5.png)