A Formigny screen or storm window hangs from two tabs at the top and then, once the frame is fully into place, is secured by a hook on the screen to an eye in the sill. Mostly: they are old, and some of the hooks and eyes are missing, stripped out, whatever. This morning as I sat at the dining table and Blake ate his breakfast on the kitchen windowsill, I sneezed. This startled Blake and I heard him flap once and then utter the cockatiel equivalent of a human "hmph" of frustration. I was already up and after him: his flap had delivered him three inches left and four up onto the screen, from which he hung by claws and beak, with tail splayed out. Remind me to check that the hook and eye are quite, quite secure.