In Preview, when I drag a PDF document from my laptop screen to an external monitor, Preview zooms in the view by a large amount--enough that I have to click the "minus" button a couple of times to get the view back to where it was. Likewise, if I move a PDF document from the external monitor to the laptop screen, Preview zooms out by the same amount.
This behavior happens with all PDF documents unless the view is set to "automatically resize", in which case moving the document doesn't cause zooming, but does cause Preview to scroll the document down about a quarter of a page.
This behavior occurs only on one of the three external monitors I've tried it on (a Viewsonic; the other two are a Dell and a Samsung), but it happens to be my work monitor. My computer is a 2011 Macbook Pro 15" running Snow Leopard. Has anyone seen this behavior, or have any ideas on what's causing it or how to stop it?