testMinimizeButton fails often

Happens on CI (Travis, Appveyor) and on my development computer.

These lines are the problem:
```java
    drag(StyleClassNameUtility.cssSelectorForOutputSocketHandleOn(desaturateStep), MouseButton
        .PRIMARY).dropTo(StyleClassNameUtility.cssSelectorForInputSocketHandleOn(blurStep));
```

For some reason, it's selecting the blur `radius` socket instead of the `image` socket.