1. Open qtdeclarative\examples\demos\samegame from Qt5's repository.
2. Make sure that a Qt5-kit is selected for the project, QTCREATORBUG-8900 might get in your way.
3. Set a breakpoint at the first line of startNewGame(...) in samegame.js.
4. Start debugging the project.
5. Click "1 Player".
   Creator hits the breakpoint.
6. In "Locals and Expressions" view, expand "gc" and "this".
7. Step over.
   "gc" and "this" are collapsed again.

Stepping should not change expanding/collapsing. When running a similar project on Qt4, this seems to work correctly.