synaptic starts from kmenu but not from root konsole (and other stuff)
 

I would appreciate help in understanding and fixing what I have done wrong. I have tried to keep this as short as possible so maybe I have left out important stuff. More info can be provided, please ask. Thanks in advance for reading and any suggestions.

Background:
Not sure of the details, but something(s) went awry before/during/after setting things up (loosely following http://techpatterns.com/forums/about1435.html) to be able to run firefox aurora instead of iceweasel on Debian. Some files were deleted as a result of an apt-get session and KDE would no longer run - that was fixed. Some packages from experimental were installed. Other things which I no longer remember also happened.

I think the best place for me to start might be if I could figure out why synaptic starts from the kmenu but gparted does not. But maybe not. Info about other programs is for context. Sorry if this is not the right place for this or if it's faq and solved, I did look. Anyway....

--------
Synaptic 0.75.3 DOES start from Kmenu BUT
omega:/home/rtq# synaptic
No protocol specified

(synaptic:5521): Gtk-WARNING **: cannot open display: :0
---------
---------
Gparted 0.10.0-1 DOES NOT start from Kmenu (no output at all that I could see), and
omega:/home/rtq# gparted
No protocol specified

(gpartedbin:5939): Gtk-WARNING **: cannot open display: :0
--------
--------
Firefox DOES NOT start from Kmenu (no output at all that I could see), and
omega:/home/rtq# firefox
No protocol specified
No protocol specified
No protocol specified
Error: cannot open display: :0

BUT

omega:/home/rtq# firefox -help
Usage: firefox [ options ... ] [URL]
where options include:

X11 options
<snippage>

so there is some life in firefox. Also, firefox will start and run normally in some circumstances not specified here for the sake of brevity.
--------
--------
Installed Versions and system info:
kdebase-bin 4:4.6.5-1
kdebase-workspace 4:4.6.5-4
xorg 1:7.6+10
X11-common 1:7.7+10
libX11-6 2:1.4.4-4
~$ cat /etc/issue
Debian GNU/Linux wheezy/sid \n \l

~$ uname -a
Linux omega 3.1.0-1-686-pae #1 SMP Sun Dec 11 20:40:16 UTC 2011 i686 GNU/Linux

~$ firefox -v
Mozilla Firefox 10.0a2

have you tried running programs with kdesu or kdesudo? i.e. kdesu synaptic

Update:

No, I haven't. I might at some point. But, as I mentioned, firefox also will only run at least some of the time and only as root. I am reluctant routinely to connect firefox as root to the net.

This is partly solved. (Also I have done some apt-get updates so some of the above version numbers may have changed.)

Re gparted, this works:
rtq@omega:~$ su-to-root -X -c /usr/sbin/gparted

Re firefox this works:
rtq@omega:~$ su-to-root -X -c /opt/firefox/firefox

But, as I said, I prefer not to run firefox as root. When I try as not root I get the following:
rtq@omega:~$ firefox
rtq@omega:~$

omega:/home/rtq# firefox
No protocol specified
No protocol specified
No protocol specified
Error: cannot open display: :0

omega:/home/rtq# firefox -v
Mozilla Firefox 11.0a2
No protocol specified

Btw, I did stfw for "Error: cannot open display: :0" among other things. What I found that seems to work (such as running startx as root) does not seem to allow me to run firefox as an unprivileged user.

For example, this works:
rtq@omega:~$ xhost local:rtq
non-network local connections being added to access control list
omega:/home/rtq# firefox

Unfortunately, it still requires running firefox as root.

I have also rtfm, but maybe not the right stuff.

Help requested and appreciated.

Ok, because gparted and synaptic both work, I'm going to mark this solved. Thanks to rizzy for his/hercomment and to others for reading.

I may start another thread for the firefox problem (which is still not resolved) after the new year.

Best wishes to all for happiness, health and honest prosperity in 2012.