TitledPane issue with ScrollPane

Unzip and run the attached nb project, which aggregates a set of TitledPane in a ScrollPane.

Run the project.

First issue :
Bun1 is not fully displayed.

Second issue :
Scroll down or open Bun2 - Bun2 jumps downwards unexpectedly.

Third Issue (probably related to second issue):
Open Bun2. Use scrollbar to position Bun2 at the top of the ScrollPane. Now close Bun2 and you will also see it jump down downwards.