- Open some project.
- Build it.
- Start running it.
- Above the Application Output tab, press the red stop button.
- If you built the project on Qt 4, Creator will write "The program has unexpectedly finished." to Application Output.
- If you built the project on Qt 5, only messages about start and exit of the program are in Application Output, no report about unexpectedly finishing.
I think the output should be same in both cases.