Re: Abort in try_window_id

[Richard Stallman]

    I have updated to Emacs CVS two weeks ago, and today I had an abort
    in try_window_id.

    12165             /* Set the cursor.  */
    12166             row = row_containing_pos (w, PT, r0, NULL, 0);
    12167             if (row)
    12168               set_cursor_from_row (w, row, current_matrix, 0, 0, 0, 
0);
    12169             else
    12170               abort ();

The question is why row_containing_pos return null.
There could be a bug in that function.  Perhaps there
is some strange situation in the data, which the code in that function
does not handle.

In order to figure out what to change, I need to know what that situation is;
in other words, why and how row_containing_pos return null.