GNU bug report logs - #81077
31.0.60; Sometimes only upper parts of text are unexpectedly displayed

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From: Markus Triska <triska@HIDDEN>
To: bug-gnu-emacs@HIDDEN
Subject: 31.0.60; Sometimes only upper parts of text are unexpectedly displayed
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To reproduce this issue, please put the following code in a file called
frameglitch.el, and then invoke Emacs with:

    $ emacs -Q -l frameglitch.el

The expectation is that "Hello!" is fully visibly displayed. However,
sometimes but not always, only an upper part of the letters is visible.

Press a key to return to regular Emacs interaction. You can do:

    M-x eval-buffer RET

on frameglitch.el as often as you like, and sometimes "Hello!" is fully
visible, and sometimes not.

The example consistently works exactly as expected for example in Emacs
versions 26.1, 29.1 and 30.2, where "Hello!" is always fully visible.

The contents of frameglitch.el follow below.

Please let me know any time if anything else is needed.

Thank you and all the best,
Markus


;; -*- lexical-binding: t; -*-

(defun glitching-frame (x y)
  (tool-bar-mode -1)
  (menu-bar-mode -1)
  (let* ((width 200)
         (height 100)
         (frame (make-frame `((parent-frame . ,(selected-frame))
                              (minibuffer . nil)
                              (left . ,x)
                              (top . ,y)
                              (internal-border-width . 0)
                              (vertical-scroll-bars . nil)
                              (left-fringe . 0)
                              (right-fringe . 0)
                              (no-special-glyphs . t) ; see #52929
                              ;; not setting the width/height causes
                              ;; mode line flickering (see #52666)
                              (width . (text-pixels . ,width))
                              (height . (text-pixels . ,height)))))
         (buf (get-buffer-create "showing the text")))
    (set-face-attribute 'default frame :height 12)
    (set-frame-width frame width nil t)
    (set-frame-height frame height nil t)
    (with-selected-frame frame
      (switch-to-buffer buf)
      (erase-buffer)
      (insert (propertize "Hello!" 'face '(:height 300)))
      (setq cursor-type nil
            mode-line-format nil))
    frame))

(let ((f (glitching-frame 0 0)))
  (read-key)
  (delete-frame f))



In GNU Emacs 31.0.60 (build 1, x86_64-pc-linux-gnu, X toolkit, Xaw
 scroll bars) of 2026-05-19 built on notebook
Repository revision: e90cafc2886dec40d241db16cc5cf89d44d34502
Repository branch: emacs-31
Windowing system distributor 'The X.Org Foundation', version 11.0.12101016
System Description: Debian GNU/Linux 13 (trixie)

Configured using:
 'configure --without-cairo --with-x-toolkit=lucid
 --with-xpm=ifavailable --with-gif=ifavailable --with-tiff=ifavailable
 --with-gnutls=ifavailable'

Configured features:
FREETYPE GLIB GMP GSETTINGS HARFBUZZ JPEG LIBXML2 MODULES NOTIFY INOTIFY
PDUMPER PNG RSVG SECCOMP SOUND THREADS TIFF TOOLKIT_SCROLL_BARS WEBP X11
XDBE XFT XIM XPM LUCID ZLIB

Important settings:
  value of $LANG: en_US.UTF-8
  value of $XMODIFIERS: @im=ibus
  locale-coding-system: utf-8-unix