Steps to reproduce

1. Open one JFR in JMC.
2. Open any screen where stacktrace is present.
3. Go to show tree view.
4. Expand the tree as per your requirement. Navigate to few levels.
5. Open another JFR and switch there.
6. Come back to previous JFR.
7. Stack trace is not retained where we left. Tree will be in collapsed to default view.

Ideally user would like to see the expanded call stack trace tree where he left. So that the comparison between the JFRs is easy.