AbstractTree notifications do not work properly

I discovered a bug when I deleted the last line in the following method in AbstractTree

```java
@Override
public void doubleClick() {
   logger.debug("Double Click Tree Item " + getText());
   select();
   treeHandler.notifyTree(getSWTWidget(), treeHandler.createEventForTree(
   getSWTWidget(), SWT.MouseDoubleClick));
   treeHandler.notifyTree(getSWTWidget(), treeHandler.createEventForTree(
   getSWTWidget(), SWT.DefaultSelection));
   logger.info("Double Clicked on: " + this);
}
```

When the logging was removed, the last notification was not called. It is because there is ```this.toString()``` in logging message and it calls Display.syncExec which somehow flushes created event.