Re: "Position Parameters" in lispref/frames.texi

[martin rudalics <rudalics@gmx.at>]

> Oh, is it trying to say that (+ -100) will shift the left edge 100
> pixels to the _left_ of the left screen edge?

That's how I understand it and how it works here on windows.

> This doesn't actually seem to work right now, which is what I think
>
> http://lists.gnu.org/archive/html/bug-gnu-emacs/2008-01/msg00058.html
>
> is saying.

Does it work for you?  Ulrich Neumerkel promised me to debug this
tomorrow (tuesday).

FWIW, the first "+" and "-" discriminate left vs right (top vs bottom)
screen edges/frame borders.  For example, "left +" specifies the left
frame border "left -" the right one.  (I don't understand why we can't
use right and bottom here.)

The second "+" and "-" indicate an offset where "+" stands for "nearer
to the center of the screen" and "-" for "farther away from the center
of the screen".  That is "left + -7" means the left frame border should
move 7 pixels to the left of the left screen edge, "left - -7" the right
frame border should move 7 pixels to the right of the right screen edge.

All this with the understanding that you cannot specify a position of
the left frame border wrt to the right screen edge.

>>     *Reminder:* if the parameter is a negative integer -POS, then POS
>>     is positive.
>
>
> Still can't parse that...

As for the manual:

In "the position of the right edge of the window with respect to the
right edge of the screen" use "frame" instead of "window".

"The value may be a positive number POS, or a list of the form `(+ POS)'
which permits specifying a negative POS value." doesn't make sense
because the connotation of "negative POS value" is ambiguous here.

"A positive value of POS counts toward the left.  *Reminder:* if the
parameter is a negative integer -POS, then POS is positive." is
ambiguous too.

IMHO, the explanations in section 29.3.5

     `(+ POSITION)'
           This specifies the position of the left or top edge of the
           window relative to the left or top edge of the screen.  The
           integer POSITION may be positive or negative; a negative
           value specifies a position outside the screen.

     `(- POSITION)'
           This specifies the position of the right or bottom edge of
           the window relative to the right or bottom edge of the
           screen.  The integer POSITION may be positive or negative; a
           negative value specifies a position outside the screen.

rate far better in this regard but should talk about "frame" instead of
"window".