Window/mouse hangs and flickers

Sorry for opening this issue. I have read your documentation a couple of times and I am pretty new to Java Swing and AssertJ. The problem that arises is, that AssertJ Swing simply cannot test my GUI because it does not even open the window properly.
I have tried to narrow this error down. Therefore I have pulled your example repository with the SimpleCopyApplication.java and the according SimpleCopyApplicationTest.java.

Just out of the box this setup works for me. But now the strange part comes in.
As soon as I simply delete everything out of the frame. so that there is just an empty JFrame left, the window and mouse hangs and the mouse starts flickering (it possibly moves pretty fast). I do have the same problem with my application even if the GUI contains something.

So in your example code i have just deleted everything out of the SimpleCopyApplication Constructor:

```
public SimpleCopyApplication() {

}
```

Can someone reproduce this error?
System: Windows 10

Here is a screenshot of the problem. And I cannot move my mouse for a couple of seconds:

And just one more question for my understanding:
To properly use your testing framework I also have to use your methods to create Labels/Textfields and so on? For example to create a Label I cannot instatiate a normal JLabel and test it, I need to use your function newLabel("name")? Maybe this is related to the fact that I am a beginner, but I did not get this just out of your documentation. It seemed to me that I can use my finished Swing GUI and just test it without any modifications. Especially because the quick start did not mention anything of it.

Thank you very much for your support and your work at AssertJ.