How to set the size of the main window?

Hi, sorry for asking this dumb question:
in the demo example of JUCE, I’d like to change the size of the main window.
I tried setSize() and setBounds() without success, both in the constructor and in resize().

All the best,

The demo does it in the app initialisation method, doesn’t it? No point trying to change it before that happens.

Thank you Jules!