[meerkat]

I understand your pain but this looks like the firmware's limitation.

When we use custom zoom, what we want to lock is the zoom level, NOT zoom level + the particular part of page., I do not want to unlock/relock to reposition the page.

As a partial workaround, either I zoom until the page show no page margin (but no clipping), perhaps with the help of bit shifting the page, or, I read it in landscape mode (optinally with zooming)