When the zoom window is first activated, its position on the original page is centered. When the zoom window is again activated, its position is the last position zoom window was located.

I wonder if it's an improvement to allow the user to choose where the zoom window magnify after tapping on the "zoom window" button. Basically should it be a two-step gesture like this: First tap on the "zoom window" button, then tap the document page where your want the zoom window to magnify.

The reason for this suggestion is that I usually find myself adjusting the location of the zoom window after I activate it.

Cheers,
Shule