it can be very useful add the possibility to see a dimension page (A4 etc.) so we can edit text and image into limits.
It is useful mostly when you export document in PDF (often especially the images are divided in 2 pages!)
For PDF, I think you have some control if you use the print panel. So choose Print, and save the PDF from there. I think if you do that, you can control page size etc.
We are aware of some issues with image pagination. That needs to be improved.