Erro Gnome-Tweak-Tool [Resolvido]

[spiga]

estou com este problema no gnome-tweak-tool alguem me da uma luz. nao sei bem o devo instalar, para corrigir. to meio perdido pois nunca tinha pega um erro desse jeito

emilio@Allen ~ $ gnome-tweak-tool
Traceback (most recent call last):
  File "/usr/bin/gnome-tweak-tool", line 21, in <module>
    gi.require_version("Gtk", "3.0")
  File "/usr/lib/python2.7/dist-packages/gi/__init__.py", line 50, in require_version
    (namespace, version))
ValueError: Namespace Gtk not available for version 3.0
Error in sys.excepthook:
Traceback (most recent call last):
  File "/usr/lib/python2.7/dist-packages/apport_python_hook.py", line 109, in apport_excepthook
    os.O_WRONLY|os.O_CREAT|os.O_EXCL, 0o600), 'w')
OSError: [Errno 2] No such file or directory: '/var/crash/_usr_bin_gnome-tweak-tool.1000.crash'

Original exception was:
Traceback (most recent call last):
  File "/usr/bin/gnome-tweak-tool", line 21, in <module>
    gi.require_version("Gtk", "3.0")
  File "/usr/lib/python2.7/dist-packages/gi/__init__.py", line 50, in require_version
    (namespace, version))
ValueError: Namespace Gtk not available for version 3.0

[spiga]

faltava instalar algumas Lib do GTK3.0