Hi there,

resizing the Emacs frame causes the background color that has been set
via a theme or directly via M-x set-background-color to be reset to a
default value, except for the parts with (visible or invisible) text on
it. Steps to reproduce:

1. Start Emacs
2. M-x set-background-color and choose any background colour you like
3. Resize the frame

The effect can be recovered by again doing M-x set-background-color or
reloading the current theme (until the next resize). See the attached
screenshots for a demonstration (order in which they were taken is
preresize - postresize - postreset).

This is 100% reproducible on my two machines here running 64-bit Arch
Linux with i3 as the window manager in an otherwise mostly XFCE
environment (i3 is a tiling window manager and as such resizes windows
all the time). Emacs is in both cases the stock emacs from the Arch
Linux repositories. The GTK theme in use is the Xfce/gtk-3.0 theme.

Greetings,
Marvin


In GNU Emacs 24.2.1 (x86_64-unknown-linux-gnu, GTK+ Version 3.6.2)
  of 2012-11-18 on eric
Windowing system distributor `The X.Org Foundation', version 11.0.11300000
Configured using:
  `configure '--prefix=/usr' '--sysconfdir=/etc' '--libexecdir=/usr/lib'
  '--localstatedir=/var' '--with-x-toolkit=gtk3' '--with-xft'
  'CFLAGS=-march=x86-64 -mtune=generic -O2 -pipe -fstack-protector
  --param=ssp-buffer-size=4 -D_FORTIFY_SOURCE=2'
  'LDFLAGS=-Wl,-O1,--sort-common,--as-needed,-z,relro''

Important settings:
   value of $LC_ALL: nil
   value of $LC_COLLATE: C
   value of $LC_CTYPE: nil
   value of $LC_MESSAGES: nil
   value of $LC_MONETARY: nil
   value of $LC_NUMERIC: nil
   value of $LC_TIME: nil
   value of $LANG: de_DE.utf8
   value of $XMODIFIERS: nil
   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:
M-x s e t - b a c k g r o u n d - c o l <tab> <return>
# 0 0 0 0 F F <return> M-x r e p o r t - e m a c s
- b u <tab> <return>

Recent messages:
For information about GNU Emacs and the GNU system, type C-h C-a.
delete-backward-char: Text is read-only

Load-path shadows:
None found.

Features:
(shadow sort gnus-util mail-extr emacsbug message format-spec rfc822 mml
easymenu mml-sec mm-decode mm-bodies mm-encode mail-parse rfc2231
mailabbrev gmm-utils mailheader sendmail regexp-opt rfc2047 rfc2045
ietf-drums mm-util mail-prsvr mail-utils time-date tooltip ediff-hook
vc-hooks lisp-float-type mwheel x-win x-dnd tool-bar dnd fontset image
fringe lisp-mode register page menu-bar rfn-eshadow timer select
scroll-bar mouse jit-lock font-lock syntax facemenu font-core frame cham
georgian utf-8-lang misc-lang vietnamese tibetan thai tai-viet lao
korean japanese hebrew greek romanian slovak czech european ethiopic
indian cyrillic chinese case-table epa-hook jka-cmpr-hook help simple
abbrev minibuffer loaddefs button faces cus-face files text-properties
overlay sha1 md5 base64 format env code-pages mule custom widget
hashtable-print-readable backquote make-network-process dbusbind
dynamic-setting system-font-setting font-render-setting move-toolbar gtk
x-toolkit x multi-tty emacs)