[Zubersoft]

If you think of A4 as a physical size, that wouldn't make sense to enlarge the page to that size on a screen that is too small to display it. If you think of it as an aspect ratio, that would cause the page to be stretched unequally in each dimension, and that stretching causes some amount of distortion. In general, I don't really think that makes sense as an option. Having said that, I do plan on supporting something similar with the cropping editor where I use A4 as an aspect ratio and adjust the cropping box to match that aspect ratio. 

Why can't you just start with "Fit Screen" as the stretching option and pinch zoom the page to the size you want? Then just adjust the scroll timing to match. This is essentially the same idea as having an A4 setting that would enlarge the page for you, but as I mentioned before, stretching a page that has an aspect ratio that does not match an A4 page means it's going to cause some undesirable stretching. If I limit the stretch to one dimension (make the width or height match A4, whichever is hit first), that is identical to just pinch zooming the page, and as mentioned before, that option doesn't really make sense on a screen that is too small to fit the page. 

I'm definitely not going to implement changes that suddenly change how the music is displayed while scrolling. It seems like a very strange scenario where you'd want the page displayed differently while scrolling versus how it is displayed by default.

Mike