[PyQt] adding keypress event

[Janwillem van Dijk]

I have small application build with Eric/Qt Designer. Even for somebody 
like me who does not really understand events, slots, signals and 
signatures this works great. But now I am stuck because I want to 
intercept the PgDn key to do something special (fire a camera).
My projcect (interacting with a camera using gphoto2) consists of the 
following files:
ui/capture_photo_form.ui (made with Qt Designer)
ui/Ui_capture_photo_form.py (Eric: Compiled Form)
ui/capture_photo_form.py (Eric: Generate Dialogue Code plus my own code)
capture_photo.py (creates application)

Please help in the form a piece of example code.
Many thanks, Janwillem