evert@localhost ~ $ unity-lobby
Error: UnityLobby requires at least GTK v2.10.0 and PyGTK v2.10.0, your versions of GTK and PyGTK are (2, 10, 6)  and  (2, 8, 6)



localhost evert # echo 'dev-python/pygtk' >> /etc/portage/package.keywords
localhost evert # emerge -s pygtk
Searching...
[ Results for search key : pygtk ]
[ Applications found : 2 ]

*  dev-python/pygtk
      Latest version available: 2.10.3
      Latest version installed: 2.8.6
      Size of files: 2,521 kB
      Homepage:      http://www.pygtk.org/
      Description:   GTK+2 bindings for Python
      License:       LGPL-2.1

*  dev-python/pygtkglext
      Latest version available: 1.0.1
      Latest version installed: 1.0.1
      Size of files: 313 kB
      Homepage:      http://gtkglext.sourceforge.net/
      Description:   Python bindings to GtkGLExt
      License:       GPL-2


localhost evert # emerge -av pygtk

These are the packages that would be merged, in order:

Calculating dependencies -
!!! All ebuilds that could satisfy ">=dev-python/pygobject-2.12.1" have been masked.
!!! One of the following masked packages is required to complete your request:
- dev-python/pygobject-2.12.1 (masked by: ~x86 keyword)
- dev-python/pygobject-2.12.3 (masked by: ~x86 keyword)
- dev-python/pygobject-2.12.2 (masked by: ~x86 keyword)

For more information, see MASKED PACKAGES section in the emerge man page or
refer to the Gentoo Handbook.
(dependency required by "dev-python/pygtk-2.10.3" [ebuild])

localhost evert # echo 'dev-python/pygtk' >> /etc/portage/package.unmask
localhost evert # emerge -av pygtk

These are the packages that would be merged, in order:

Calculating dependencies -
!!! All ebuilds that could satisfy ">=dev-python/pygobject-2.12.1" have been masked.
!!! One of the following masked packages is required to complete your request:
- dev-python/pygobject-2.12.1 (masked by: ~x86 keyword)
- dev-python/pygobject-2.12.3 (masked by: ~x86 keyword)
- dev-python/pygobject-2.12.2 (masked by: ~x86 keyword)

For more information, see MASKED PACKAGES section in the emerge man page or
refer to the Gentoo Handbook.
(dependency required by "dev-python/pygtk-2.10.3" [ebuild])

localhost evert # echo 'dev-python/pygobject' >> /etc/portage/package.keywors
localhost evert # echo 'dev-python/pygobject' >> /etc/portage/package.unmask
localhost evert # emerge -av pygtk

These are the packages that would be merged, in order:

Calculating dependencies -
!!! All ebuilds that could satisfy ">=dev-python/pygobject-2.12.1" have been masked.
!!! One of the following masked packages is required to complete your request:
- dev-python/pygobject-2.12.1 (masked by: ~x86 keyword)
- dev-python/pygobject-2.12.3 (masked by: ~x86 keyword)
- dev-python/pygobject-2.12.2 (masked by: ~x86 keyword)

For more information, see MASKED PACKAGES section in the emerge man page or
refer to the Gentoo Handbook.
(dependency required by "dev-python/pygtk-2.10.3" [ebuild])

localhost evert # emerge -av pygobject

These are the packages that would be merged, in order:

Calculating dependencies
!!! All ebuilds that could satisfy "pygobject" have been masked.
!!! One of the following masked packages is required to complete your request:
- dev-python/pygobject-2.12.1 (masked by: ~x86 keyword)
- dev-python/pygobject-2.12.3 (masked by: ~x86 keyword)
- dev-python/pygobject-2.12.2 (masked by: ~x86 keyword)

For more information, see MASKED PACKAGES section in the emerge man page or
refer to the Gentoo Handbook.

localhost evert # echo 'dev-python/pygobject' >> /etc/portage/package.unmask
localhost evert # echo 'dev-python/pygobject' >> /etc/portage/package.keywors
localhost evert # emerge -av pygobject

These are the packages that would be merged, in order:

Calculating dependencies
!!! All ebuilds that could satisfy "pygobject" have been masked.
!!! One of the following masked packages is required to complete your request:
- dev-python/pygobject-2.12.1 (masked by: ~x86 keyword)
- dev-python/pygobject-2.12.3 (masked by: ~x86 keyword)
- dev-python/pygobject-2.12.2 (masked by: ~x86 keyword)

For more information, see MASKED PACKAGES section in the emerge man page or
refer to the Gentoo Handbook.

localhost evert # nano /etc/portage/package.unmask
localhost evert # nano /etc/portage/package.keywords
localhost evert # emerge -av pygobject

These are the packages that would be merged, in order:

Calculating dependencies... done!
[blocks B     ] <dev-python/pygtk-2.9 (is blocking dev-python/pygobject-2.12.3)
[ebuild  N    ] dev-python/pygobject-2.12.3  USE="-debug -doc" 331 kB

Total size of downloads: 331 kB

!!! Error: The above package list contains packages which cannot be installed
!!!        at the same time on the same system.

For more information about Blocked Packages, please refer to the following
section of the Gentoo Linux x86 Handbook (architecture is irrelevant):

http://www.gentoo.org/doc/en/handbook/handbook-x86.xml?full=1#blocked