Text Selection Doesn't Align

[cmcnicholas]

Hi, I have put together the single page viewer in my application, easy enough to get working.

I am seeing drift though as I scroll down the page when it comes to text selection, the positioning isn't correct towards the bottom of the document but the top looks correct (like its drift that is amplified the further from the top of the document 0%)

e.g. bottom of doc:

e.g. top of doc: