When using the box cursor-type the cursor is stretched over the glyph under it, acting as if the value of x-stretch-cursor were non-nil. The value of that variable doesn't seem to have any effect. I'm attaching a screenshot of emacs -Q with a cursor over a tab character. In GNU Emacs 28.0.50 (build 1, x86_64-pc-linux-gnu, GTK+ Version 3.24.20, cairo version 1.16.0) of 2021-09-14 built on lab-pc42 Repository revision: 4c49ec7f865bdad1629d2f125f71f4e506b258f2 Repository branch: feature/pgtk Windowing system distributor 'System Description: Ubuntu 20.04.3 LTS Configured using: 'configure --with-native-compilation --with-pgtk --prefix=/home/user/.local 'CFLAGS=-O2 -march=native -fomit-frame-pointer'' Configured features: CAIRO DBUS FREETYPE GIF GLIB GMP GNUTLS GSETTINGS HARFBUZZ JPEG JSON LIBSELINUX MODULES NATIVE_COMP NOTIFY INOTIFY PDUMPER PGTK PNG SECCOMP SOUND THREADS TIFF TOOLKIT_SCROLL_BARS XIM GTK3 ZLIB