Bug: Undo paste issue

Here is a Jing of the issue done on the tlf example editor. I will go through the process to reproduce it as well.

http://www.screencast.com/users/mkracum/folders/Jing/media/e4ce9354-ccd4-46f7-aa84-1a88ba752d48

Steps to reproduce:

1. Write two lines of text.
2. Copy the return character and the last word of the first line.
3. Paste it at the end of the first line.
4. Undo. (The return simply disappears, it should still be there)

My best guess is that the paste says it has the length of the word plus the return char that it is pasting, but when it pastes the return character that was already there merges with the one you are pasting. When you undo it thinks that it should undo the length of the word plus the return, but in actuality the return wasn't added, it merged with the one that was there causing an extra char to be removed.

Looking for a solution. I have been digging for the problem, but I figure someone may be able to narrow my search a bit. It is causing RTEs in certain cases, so I need to get it resolved.

Thanks,

-Matt