swap feature problems

a) no warning if contents modified, just does the swap and lose all changes

b) when do a diff from VC, titles not updated on swap

before
    dirdiff.py (working, repository)
        <fullpath>/dirdiff.py
        dirdiff.py - repository
after
    dirdiff.py (working, repository)
        /tmp/...
        dirdiff.py - repository

should be
    dirdiff.py (repository, working)
        dirdiff.py - repository
        <fullpath>/dirdiff.py

c) when doing diff where one of the files originated as 'unnamed' swapping just puts the real file into the other pane leading to a diff of the same file.

before
    <unnamed> - test88.py
        File 1
        <fullpath>/test88.py
after
    test88.py - test88,py
        <fullpath>/test88.py
        <fullpath>/test88.py
should be
    test88.py - <unnamed>
        <fullpath>/test88.py
        File 1