Comment 1 for bug 85146

Notes from the backtrace: The crash is due to a call to abort() at xdisp.c:12026 (which emacs then catches and rethrows, in fatal_error_signal() in emacs). It is a deliberate abortion (fall-through assertion) in try_window_id, at the final else clause of:

if (first_unchanged_at_end_row
      && first_unchanged_at_end_row->y < it.last_visible_y
      && !last_text_row_at_end)
 ...
else if (last_text_row_at_end)
 ...
else if (last_text_row)
 ...
else if (first_unchanged_at_end_row == NULL
    && last_text_row == NULL
    && last_text_row_at_end == NULL)
 ...
else
  abort(); // <<=============

try_window_id() has been passed the value "selected_window"; so there must be something wrong with that value or the state of the currently selected window (I'd guess the latter).