Finestra pop-up, which is generic but the only translation, half translation, available. Click dummy is not so common, I guess, even in technical contexts. Finestra pop-up di passaggio would be complete but maybe uselessly complete.
I'm not sure I have understood what a click dummy is, but I've googled it too. I'm still confused, but could it be a pulsante provvisorio
or a pulsante esemplificativo?
If I'm programming a web site, I place a button, or a clickable picture, just for pogramming purposes, or to show it to the client. Isn't that a click dummy?
If it doesn't pop up then pulsante provvisorio is quite correct.
Probably I got what a click dummy is http://www.medien.ifi.lmu.de/filead...exercise/uebung4/dummy_js/no-sound-index.html
A button, but better a whole interface, supposed to recall functions not yet implemented or dummily implemented (if you click on call the phone doesn't really call but the action supposed to happen is shown). It is used to show an interface to the end user while still developing the backside of the application.
So probably in italian I'd translate it with demo: il nostro cliente sta per condurre un test di usabilità con una versione dimostrativa; we're generic and lazy and don't want to mess with that exact button, unless it's technically needed for sake of precision.