I get this from dbx:
*a11y = {
    parent = {
        parent = {
            parent            = {
                g_type_instance = {
                    g_class = 0x9d1bc90
                }
                ref_count       = 1U
                qdata           = 0x9d1a830
            }
            description       = (nil)
            name              = 0x9d18c38 "Status"
            accessible_parent = (nil)
            role              = ATK_ROLE_TABLE_COLUMN_HEADER
            relation_set      = 0x9d19110
            layer             = ATK_LAYER_WIDGET
        }
    }
}

which field do you mean? accessible_parent?

This is the component field of the accessible object used
everywhere in Orca. See the __get_component routine starting
at line 1045 in:

http://cvs.gnome.org/viewcvs/orca/src/orca/atspi.py?annotate=1.38

Created attachment 308336 [details] [review]
Proposed patch.

This bug is still present (I'm seeing the behavior described in the related orca bug).

Thanks for the patch. Even I'm not able (I do not know how) to test the patch, it looks fine. I added there some safety checks and a slight coding-style change. There were also introduced two compiler warnings, which I fixed as well.

> gal-a11y-e-table-column-header.c: In function 'gal_a11y_e_table_column_header_get_extents':
> gal-a11y-e-table-column-header.c:218:26: warning: passing argument 1 of 'atk_object_get_parent' from incompatible pointer type
>
> gal-a11y-e-table-column-header.c:218:3: warning: passing argument 1 of 'atk_component_get_position' from incompatible pointer type

Created commit 3dafc79 in evo master (3.17.90+)
Created commit 2a6bdb6 in evo gnome-3-16 (3.16.5+)