Bad remote file systems can change mtime unexpectedly,
and then there is the problem that git rebase and similar
operations like to change the files and then change them back,
modifying the mtimes but not the content.
Avoid spurious Put errors on both of those by checking file
content.
(False positive "modified since last read" make the real ones
difficult to notice.)
If the mouse was in the tag of the old window,
it was most likely pointing at Del. If bringing up a
new window from below and not moving the mouse
somewhere else, adjust it so that it ends up pointing
at Del in the replacement window's tag too.
This makes it easy to Del a sequence of windows in
a column, from top to bottom.
http://www.youtube.com/watch?v=ET8w6RT6u5M
R=r
http://codereview.appspot.com/6558047
