i propose a change to the way line-move-to-column to enable
insensitivity to fields.  without this change, modes that make certain
uses of fields sacrifice column retention in line motion.  i consider
that a bug, and this a bug fix.

in my under-development allout extensions, i'm using field boundaries
to distinguish between an outline item's structural elements (the
guide lines and topic bullet area) and the item's content,
specifically the content on the item's head line:

| | | > here's the content.  the stuff before "here's" is the bullet
and guidelines.

this is working exactly as i need - cursor motion from within the
headline content stops when it first hits the start of the content,
yet will move into the structure area (for hot-spot navigation) with a
subsequent ^A.

the bug is that i can't use text fields this way without sacrificing
column retention on line moves, as far as i can tell.
line-move-to-column is hard-wired to respect fields when seeking the
prior positions column, so that moving the cursor between topics
usually leaves the cursor at column 0, which is almost always not what
the user wants.

my patch introduces a new lisp-level variable,
`line-move-ignore-fields', and a condition in line-move-to-column to
obey that variable.  the default setting of line-move-ignore-fields is
nil, so the current behavior remains.  my allout extension sets it to
get the behavior it needs.

(i made it a lisp-level rather than customization variable because i
expect that it's a modal, not user policy.  i feel the same way about
line-move-ignore-invisible, though, so i'm breaking with that
precedent, and could be persuaded to have the variable i'm introducing
be customizable.)

i would be interested to hear if i missed some better way to achieve
either the cursor motion i want in the headline, without using fields,
or have column retention without adding the field sensitivity
inhibition, as i'm doing.  barring that, i think this is a necessary
bug fix.

the patch is attached, and here's the ChangeLog entry:

2006-08-22  Ken Manheimer  <ken.manheimer@gmail.com>

	* simple.el (line-move-ignore-fields): New lisp-level variable for
	overriding line-move-to-column's sensitivity to fields when doing
	column positioning.
	(line-move-to-column): Respect line-move-ignore-fields.

-- 
ken
ken.manheimer@gmail.com
http://myriadicity.net