First of all I would like to mention that it has been only 4 days since I switched to funtoo from arch. I am enjoying it a lot. However understanding portage is being challenging. What I have encountered today is after updating my system I tried to install a thunar and emerge complained about a necessary change.
# > emerge -av xfce-base/thunar
These are the packages that would be merged, in order:
Calculating dependencies... done!
The following USE changes are necessary to proceed:
(see "package.use" in the portage(5) man page for more details)
# required by dev-python/subunit-1.2.0