Alt-Gr key for instant full screen image in Picasa

I've long used the very useful shortcut of pressing the Ctrl and Alt keys together when hovering the mouse over an image thumbnail in Picasa as a way of zooming that thumbnail out to full screen size.  (Actually you need to press the keys so that you press Ctrl first, then keep that held down whilst you also press Alt)

However, I've just found out that there is an even simpler way to do the same - the right Alt key (normally marked Alt-Gr) will also zoom the image, without needing anyout key to be pressed with it.