Add line modification indicator as in Kate

To make it even more useful a way to navigate through modified saved/unsaved lines could be added, such as a keyboard shortcut or perhaps as an option in the 'Search' menu.

I'm glad that you've reported this bug report. However when i take a look at kate's line feature.
I don't think that it is that necessary. Scratch puts a "*" in the tab as soon as you modify the source code of your document.
Check it out.

I don't see the *, perhaps a 2.1 feature (I'm using 2.0)? In any case that is a very different feature you're talking about. If I understand correctly, the * only tells me something inside the file has been modified in this session. I still have no idea what it was. With big files or files a user keeps open for a long time while making modifications, this is a big issuesp eciallyly given Scratch's instant save. Say I made a small change and now I need to undo it but I don't remember which line I modified (quite possible with large code files that repeat similar lines throughout it) The only option would be to hit Ctrl+Z and undo every change in the middle until I hit that one.

something more specific like Kate does could be implemented through a plugin.