Hope this makes sense...LOL
I tried selecting several images and the selection size seems random.
Ah, I understand now. What you're describing as a selection size is what I would call the zoomed area (the selection of the thumbnails does not change.)
Well I can tell you that it isn't random and is in fact entirely predictable in practice. Basically the feature keeps the thumbnail you're zooming fully visible and uses the largest remaining rectangle to show the zoomed pixels. I did it this way because I don't like some of the other methods I've seen where new windows pop up and obscure parts of the thumbnail, or force you to drag around a virtual magnifying glass. This method requires no window creation/destruction and is very fast. Also because no window is created/destroyed, keyboard and mouse focus does not change either.
So back to your question as to how to make it consistent. There are no user controls over its behavior. It works as I described above.
-Kirk
