Buggy Tab to Tab Stop in EMACS 165

[David Eppstein <Eppstein@CS.COLUMBIA.EDU>]

This is with EMACS 165 here at CS.COLUMBIA.EDU.

^R Tab to Tab Stop (the default tab for text mode) has problems when
there is text above the top of the screen.  I can duplicate the
problem by making a file of a half dozen lines, scrolling it one line
with M-1 C-V, going to the end of the file, and typing several tabs.
& Xindent gets called with out of order arguments, producing an AOR.

I couldn't get it to happen when single stepping (a likely story).
My theory is that the FM that goes to the current column in the
scratch buffer is being led astray, but it could be the following
FS SHPOS$ (the first one is right, not surprising since its in the
buffer that it expects to be in).  Anyway, I made a function that
worked by doing 0F[WINDOW$ and then chaining to the old definition,
so that seems like the right fix.
					David