I just built Qt Creator 3.5.81 from source.
I have two iPhones (both on ios 8.4) connected to the computer, one is a development device that is in the "Ready to Use" state. The other is in a "Connected" state, but is not used for development, so I don't want it to be deployable.
When a device in the Connected state is plugged in (and continuing until Qt Creator is restarted, my active window frequently loses focus for a few microseconds at a time.
Perfectly reproducible on my setup. Has no problem if only the development device is connected. My not-from-source Qt Creator (3.3.0) has no problem.
I wrote a quick python script to determine what was stealing the focus and quantify how often. Output is the number of microseconds since starting and the app who has focus, any time focus is changed.
(happy to include a longer time period, but this seems to demonstrate the issue.)