Eli Zaretskii <eliz@gnu.org> writes:

>> From: Rainer M Krug <Rainer@krugs.de>
>> Cc: 21428@debbugs.gnu.org,  mituharu+bug-gnu-emacs-mac@math.s.chiba-u.ac.jp
>> Date: Tue, 29 Sep 2015 10:01:56 +0200
>> 
>> ,----
>> | (gdb) frame 2
>> | #2  0x000000010008e4e6 in push_prefix_prop (it=0x7fff5fbf7f18, prop=4591275764) at xdisp.c:19809
>> | 19809	  eassert (it->method == GET_FROM_BUFFER
>> | (gdb) p it->sp
>> | $5 = 1
>> | (gdb) p it->stack[it->sp - 1].method
>> | $6 = GET_FROM_BUFFER
>> | (gdb) p it->stack[it->sp - 1].current
>> | $7 = {
>> |   pos = {
>> |     charpos = 175,
>> |     bytepos = 175
>> |   },
>> |   overlay_string_index = -1,
>> |   string_pos = {
>> |     charpos = -1,
>> |     bytepos = -1
>> |   },
>> |   dpvec_index = -1
>> | }
>> | (gdb)
>> `----
>> 
>> >
>> >   (gdb) pgrowx it->glyph_row
>> >   (gdb) p it->object
>> >   (gdb) xtype
>> 
>> OK
>> 
>> ,----
>> | (gdb) pgrowx it->glyph_row
>> | (gdb)  p it->object
>> | $8 = 4590394133
>> | (gdb) xtype
>> | Lisp_Vectorlike
>> | PVEC_BUFFER
>> | (gdb)
>> `----
>
> In this same frame #2, what does this produce:
>
>   (gdb) p prop
>   (gdb) xtype
>
> If the last command says "Lisp_String", follow it with "xstring"; if
> it says "Lisp_Cons", follow it with "xcar" and "xsymbol".

,----
| (gdb) frame 2
| #2  0x000000010008e4e6 in push_prefix_prop (it=0x7fff5fbf7f18, prop=4591275764) at xdisp.c:19809
| 19809	  eassert (it->method == GET_FROM_BUFFER
| (gdb) p prop
| $16 = 4591275764
| (gdb) xtype
| Lisp_String
| (gdb) xstring
| $17 = (struct Lisp_String *) 0x111a94ef0
| "* "
| (gdb)
`----

>
> Also, can you recreate the same buffer in a fresh session, and tell me
> what kind of text properties and overlays you have at or around buffer
> position 175?

175 is under an LaTeX preview in the first formula in the screenshot,
the "g" in "\begin" (or somewhere there - I continued working on the file)

,----
| #+LaTeX_header: \usepackage{amsmath} %% needed explicitely for org-preview-latex
| 
| * General conditions
| The general conditions for all parametrizations are the following:
| 
| \begin{equation}
|      x=\sqrt{b}
| \end{equation}
`----

The face is
,----
| Face: default (sample) (customize this face)
| 
| Documentation:
| Basic default face.
| 
| Defined in ‘faces.el’.
| 
|            Family: Source Code Pro
|           Foundry: nil
|             Width: normal
|            Height: 140
|            Weight: normal
|             Slant: normal
|        Foreground: #333333
| DistantForeground: unspecified
|        Background: #FFFFFF
|         Underline: nil
|          Overline: nil
|    Strike-through: nil
|               Box: nil
|           Inverse: nil
|           Stipple: nil
|              Font: #<font-object -*-Source Code Pro-normal-normal-normal-*-14-*-*-*-m-0-iso10646-1>
|           Fontset: -*-Source Code Pro-normal-normal-normal-*-14-*-*-*-m-0-fontset-auto1
|           Inherit: nil
`----

>
> Thanks.