I've just encountered a weird behaviour. It is not really important, but can sometime gets confusing.
Here is how to reproduce it :
1. Open an existing document 2. Write some code, anything, anywhere 3. Save 4. Select the code you just wrote and cut it (CTRL+X) (the little * appears near the name of your document) 5. Paste (CTRL+V) your code at the exact same spot 6. Save your document again (the little * disappears) 7. Undo last operation (CTRL + Z) 8. Choose an other part of your document and paste (CTRL+V) your code here (ie. do not paste the code where it was before, put it somewhere else)
Your document has been modified since your last save, but the little * will still disappear (indicating that no change had been made), which is incorrect.