The overlay with t value has precedence over other overlays. If the problem occurs, I can run the following function, and it will get fixed in existing windows. However if I create a new window, it will show only text. If I press + in that window, a new overlay will be created. Perhaps the t overlay was meant to be the default, and someone misunderstood it's effect.(defun 13887-fix-helper1 ()(interactive)(let* ((ovs (overlays-at (point)))(ov-t (find-if (lambda (ov) (eq (overlay-get ov 'window) t))ovs)))(when ov-t (delete-overlay ov-t))))Here is one more helper function which might be useful.(defun 13887-own-overlay-present-p ()(interactive)(let* ((ovs (overlays-at (point))))(find-if (lambda (ov) (eq (overlay-get ov 'window)(selected-window)))ovs)))