bug#25408: Remove Decorations Around Emacs Frame (Windows OS)

[Eli Zaretskii <eliz@gnu.org>]

> From: Clément Pit-Claudel <cpitclaudel@gmail.com>
> Date: Fri, 5 May 2017 20:06:46 -0400
> Cc: 25408@debbugs.gnu.org
> 
> I've run into another small issue: there doesn't seem to be a way to turn off truncation marks in tooltip frames. Is that correct? This bit of xdisp.c seems to take care of that for Emacs' default tip frame; is there a way to emulate this for Lisp-created frames?
> 
>   /* Get dimensions of truncation and continuation glyphs.  These are
>      displayed as fringe bitmaps under X, but we need them for such
>      frames when the fringes are turned off.  But leave the dimensions
>      zero for tooltip frames, as these glyphs look ugly there and also
>      sabotage calculations of tooltip dimensions in x-show-tip.  */
> #ifdef HAVE_WINDOW_SYSTEM
>   if (!(FRAME_WINDOW_P (it->f)
> 	&& FRAMEP (tip_frame)
> 	&& it->f == XFRAME (tip_frame)))
> #endif

Doing that will have a disadvantage: text will be truncated on
display, but there will be no visual cue for that truncation.  Tooltip
frames don't suffer from this problem, because their size is computed
in advance to have the text fit exactly on the line, but AFAIU these
"undecorated" frames are just normal frames in that regard, so they
will be adversely affected.

Therefore, if we are going to allow disabling truncation and
continuation glyphs on such frames, it should be via a frame parameter
which is by default off.