When running emerge on a package, we got this error:

# emerge -pv gnome-base/gnome

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

Calculating dependencies... done!

emerge: there are no ebuilds built with USE flags to satisfy ">=virtual/poppler-glib-0.8[cairo]".
!!! One of the following packages is required to complete your request:
- virtual/poppler-glib-0.10.4 (Change USE: +cairo)
(dependency required by "app-text/evince-2.24.2" [ebuild])
(dependency required by "gnome-base/gnome-2.24.1" [ebuild])
(dependency required by "gnome-base/gnome" [argument])

To fix that, add the following line into /etc/portage/package.use:

app-text/poppler-bindings gtk cairo
virtual/poppler-glib cairo