Re: mouse-drag-mode-line should maybe use window-tree

[Richard M. Stallman]

    Could you explain the choice of identifier?  I have a hard time 
understanding
    what "adjust-window-trailing-edge" can mean.  What's a trailing edge?

A trailing edge is the bottom or right edge.
Can you think of a better name for that?

    Couldn't we just change the `preserve-before' argument (which is new in
    Emacs-22 anyway) instead?

We could, but note that the new definition would be a cumbersome
combination of meanings:

    Don't move the predecessor windows.
    Don't delete any windows.
    Don't shring non-adjacent windows.

For this meaning, I think it is better to use a different function.
However, maybe we should eliminate the PRESERVE-BEFORE argument now.
It was an attempt at doing what we have now done better; perhaps
we should get rid of it rather than release it.