Background color in emacs on vncserver

[Tomasz Gajewski]

I'm often using emacs on remote vnc server I get different background
color under text and different in the rest of buffer even though I'm
setting them both to the same color. Effect is not annoying when using
vnc with full color but when using vncviewer with limited colors
(LowColourLevel=2) it can look really ugly, as can be seen on attached
image.

emacs_colors.png
Description: PNG image

Do you know where is the source of problem? Different definition of
color used for background and background under text?

This is relevant part of my .emacs file.

(custom-set-variables
 ;; custom-set-variables was added by Custom.
 ;; If you edit it by hand, you could mess it up, so be careful.
 ;; Your init file should contain only one such instance.
 ;; If there is more than one, they won't work right.
 '(default-frame-alist (quote ((foreground-color . "Wheat") (background-color . 
"dark slate gray") (width . 204) (height . 58)))))
(custom-set-faces
 ;; custom-set-faces was added by Custom.
 ;; If you edit it by hand, you could mess it up, so be careful.
 ;; Your init file should contain only one such instance.
 ;; If there is more than one, they won't work right.
 '(default ((t (:inherit nil :stipple nil :background "dark slate gray" 
:foreground "Wheat" :inverse-video nil :box nil :strike-through nil :overline 
nil :underline nil :slant normal :weight normal :height 101 :width normal 
:foundry "unknown" :family "Droid Sans Mono")))))

I use emacs from ubuntu:

GNU Emacs 24.3.1 (x86_64-pc-linux-gnu, GTK+ Version 3.10.7) of 2014-03-07 on 
lamiak, modified by Debian

-- 
Tomasz