When pop-up-frames is non-nil and calendar is called a duplicate frame is created. To reproduce the issue do: (setq pop-up-frames 'graphic-only) (calendar) from a raw emacs -Q. This can be fixed by the following advice: (defadvice calendar (around disable-pop-up-frames activate) "Disable pop-up-frames while this is going on, otherwise we get extra useless frames." (let ((pop-up-frames 'nil)) ad-do-it)) so presumably all that is needed to fix the issue is a similar let block inside the calendar function. The output that generated by report-emacs-bug follows: In GNU Emacs 24.3.1 (x86_64-pc-linux-gnu, GTK+ Version 3.10.7) of 2014-03-07 on lamiak, modified by Debian Windowing system distributor `The X.Org Foundation', version 11.0.11501000 System Description: Ubuntu 14.04.1 LTS Configured using: `configure '--build' 'x86_64-linux-gnu' '--build' 'x86_64-linux-gnu' '--prefix=/usr' '--sharedstatedir=/var/lib' '--libexecdir=/usr/lib' '--localstatedir=/var/lib' '--infodir=/usr/share/info' '--mandir=/usr/share/man' '--with-pop=yes' '--enable-locallisppath=/etc/emacs24:/etc/emacs:/usr/local/share/emacs/24.3/site-lisp:/usr/local/share/emacs/site-lisp:/usr/share/emacs/24.3/site-lisp:/usr/share/emacs/site-lisp' '--with-crt-dir=/usr/lib/x86_64-linux-gnu' '--with-x=yes' '--with-x-toolkit=gtk3' '--with-toolkit-scroll-bars' 'build_alias=x86_64-linux-gnu' 'CFLAGS=-g -O2 -fstack-protector --param=ssp-buffer-size=4 -Wformat -Werror=format-security -Wall' 'LDFLAGS=-Wl,-Bsymbolic-functions -Wl,-z,relro' 'CPPFLAGS=-D_FORTIFY_SOURCE=2'' Important settings: value of $LANG: en_GB.UTF-8 locale-coding-system: utf-8-unix default enable-multibyte-characters: t Major mode: Lisp Interaction Minor modes in effect: tooltip-mode: t mouse-wheel-mode: t tool-bar-mode: t menu-bar-mode: t file-name-shadow-mode: t global-font-lock-mode: t font-lock-mode: t blink-cursor-mode: t auto-composition-mode: t auto-encryption-mode: t auto-compression-mode: t line-number-mode: t transient-mark-mode: t Recent input: