Re: no good way to highlight rectangle while region is highlighted

[Ehud Karni]

On Fri, 27 Jul 2007 14:27:49, Joe Wells wrote:
>
> "Ehud Karni" <address@hidden> writes:
>
> > The overlay is set to priority 99 and I sure see it OVER the region.
>
> How is this possible?  From (info "(elisp)Displaying Faces"):
>
>      "If these various sources together specify more than one face for a
>   particular character, Emacs merges the attributes of the various faces
                                ^^^^^^
>   specified.  For each attribute, Emacs tries first the face of any
>   special glyph; then the face for region highlighting, if appropriate;
>   then the faces specified by overlays, followed by those specified by
>   text properties, then the `mode-line' or `mode-line-inactive' or
>   `header-line' face (if in a mode line or a header line), and last the
>   `default' face."
>
> So the only faces which can override the "region" face are the faces
> for glyphs set with display tables.  Overlays can't do that.  Because
> the default "region" face sets a background color, there is no way an
> overlay can override the background color of the region.

I think the keyword is "merges" that you somehow ignored.

> >> I notice that your code modifies the buffer.  This is very undesirable
> >> for the purpose I have in mind (which is constantly showing the
> >> current rectangle).
> >
> > The code does NOT modify the buffer (you can check it on read only
> > buffer), please try it before you state such observation.
>
> Your goto-col function contains code to modify the buffer.  I assumed
> that this code was used (because otherwise why would it be there?).
> (By the way (just curious), but why aren't you using Emacs's standard
> move-to-column function instead?)

My `goto-col' is used for other purposes too. Here it is used ONLY with
the NOSPC arg set to t.

> Anyway, I couldn't try your code because it is incomplete.  As far as
> I can tell, the entry point in what you supplied is mark-set-face and
> this merely raises an error because there is no code to assign values
> to the variables mark-1st and mark-2nd that it depends on.

The code is a small part of a much larger (1320 lines) package.

Here is sample code to set mark-1st to current cursor position.
(setq mark-1st (cons
                   (save-excursion (beginning-of-line) (point-marker))
                   (col (1- (column-no)))))

Ehud.


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