Why do electric windows only work with ignition on?

[rcx106]

I'm doing some rewiring in my Vitara, to wire up the Hellas, diff lock compressor, and new alarm and some other little bits. While I'm at it I'm considering any other tweaks, and one annoyance is that the electric windows don't work if the ignition is not on.

So one guy told me this is to stop the battery draining. Maybe because the leccy windows use relays. Is this right?

Considering one of those modules that attaches to the car alarm and closes the windows when the alarm is switched on. How do these devices know that the window has closed? The Vitara does not have any sensor or intelligence in the windows at all. The motor pumps for as long as the user is pressing the button.