Copy-and-paste copies the document type from one document to another. Is it meant to do that?
Steps to reproduce the problem in 20091118:
1. Make a new page with ctrl-n.
2. Note that the document type in the status bar is Plain Text.
3. Change that document type to Python.
4. Type this Python text: "#hello".
5. ctrl-a, ctrl-c
6. Make another page with crtl-n.
7. Note that the document type of the new page is Plain Text.
9. Note that the document type has changed to Python and that the "#hello" has Python syntax highlighting applied to it.
10. Click on the document type in the status bar.
11. Note that there is a check mark next to Plain Text -- which disagrees with what is displayed in #9.
An additional weird thing is that this new page uses my Plain Text tab-to-spaces setting instead of my Python one.