gksudo qemu -hda /dev/loop0

gksudo qemu -hda /dev/loop0

(gksudo:31775): Gtk-WARNING **: Unable to locate theme engine in module_path: "pixmap",

(gksudo:31775): Gtk-WARNING **: Unable to locate theme engine in module_path: "pixmap",

(gksudo:31775): Gtk-WARNING **: Unable to locate theme engine in module_path: "pixmap",

(gksudo:31775): Gtk-WARNING **: Unable to locate theme engine in module_path: "pixmap",
GKsu version 2.0.2

Usage: gksudo [-u <user>] [options] <command>

  --debug, -d
    Print information on the screen that might be
    useful for diagnosing and/or solving problems.

  --user <user>, -u <user>
    Call <command> as the specified user.

  --disable-grab, -g
    Disable the "locking" of the keyboard, mouse,
    and focus done by the program when asking for
    password.
  --prompt, -P
    Ask the user if they want to have their keyboard
    and mouse grabbed before doing so.
  --preserve-env, -k
    Preserve the current environments, does not set $HOME
    nor $PATH, for example.
  --login, -l
    Make this a login shell. Beware this may cause
    problems with the Xauthority magic. Run xhost
    to allow the target user to open windows on your
    display!

  --description <description|file>, -D <description|file>
    Provide a descriptive name for the command to
    be used in the default message, making it nicer.
    You can also provide the absolute path for a
    .desktop file. The Name key for will be used in
    this case.
  --message <message>, -m <message>
    Replace the standard message shown to ask for
    password for the argument passed to the option.
    Only use this if --description does not suffice.

  --print-pass, -p
    Ask gksu to print the password to stdout, just
    like ssh-askpass. Useful to use in scripts with
    programs that accept receiving the password on
    stdin.

  --sudo-mode, -S
    Make GKSu use sudo instead of su, as if it had been
    run as "gksudo".
  --su-mode, -w
    Make GKSu use su, instead of using libgksu's
    default.
san@san-desktop:~$