Steps to reproduce:
- Drag'n'drop Accordion onto Content Panel
- Drag'n'drop TitledPane as the Accordion child
- Double click Accordion entry in Hierarchy tree
- Click outside the edit box to finish editing
RESULT: Two original children of Accordion got expanded. The third one doesn't.

This is incorrect as:
1) There is a difference in behavior between original two and added TitledPanes.
2) Accordion logic doesn't allow more than 1 TitledPane to be opened at a time.