> 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

Please try the attached patch (I only checked whether it compiles and
builds on Windows).  You have to add a non-nil 'no-special-glyphs' frame
parameter to suppress such glyphs.

And please test the new behavior for tooltip frames as well.

Thanks, martin