[zubspace]

There are so many ways to layout text on a PDF page, that this is nearly impossible to implement for all scenarios. I don't know a PDF editor which works in all cases.

Sometimes text is positioned absolute to the page border, sometimes relative to other elements, where moving a word shifts all following elements around. There can be multiple matrices involved for positioning text elements. Sometimes text elements are all positioned independently, sometimes by using newlines with custom size. Text elements can span multiple lines or words but sometimes each letter is a single text element where it is even hard to determine, which letters go together or if there's meant to be a space. Additionally fonts can be subsetted, where it's impossible to use other unused letters without knowing the original font. And than there can be OCR'ed PDF's, where an image of scanned text is overlayed on top of the real text. Oh and there can be clipping paths: Rectangles which erase all text below.

And each PDF-Producer creates a different PDF structure.

For reading, PDF's are awesome. For editing, PDF's are a nightmare.