Basically, you can’t at the moment within the PsychoPy app. The Coder interface isn’t really designed to be a full-fledged IDE, just a basic editor for newbies to get going.
For a more sophisticated editor you should look into:
- Spyder (open source)
- PyCharm (commercial but with a free community edition that’s great - my personal favourite)
- WingIDE
- many others via google
It just isn’t worth us making this a priority at the moment given the vastly superior other options