Needs to make sure it works and that it does what https://forum.kde.org/viewtopic.php?f=251&t=122750 describes

One thing that is important to keep in mind is what to do with Undo/Redo after save. As far as i remember one of the pain points was that at least in PDF you could not undo a after save. This needs to be double checked, make sure the UI is correctly updated, documented on the manual, etc. And ideally solved, since it's always nice to have proper undo/redo independent of having saved the file.