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

Calculating dependencies ...

!!! Problem resolving dependencies for =media-video/mkvtoolnix-102.0
 done!
Dependency resolution took 0.83 s (backtrack: 0/20).


!!! The ebuild selected to satisfy "=media-video/mkvtoolnix-102.0" has unmet requirements.
- media-video/mkvtoolnix-102.0::gentoo USE="dbus nls -debug -dvd -gui (-pch) -test -verify-sig"

  The following REQUIRED_USE flag constraints are unsatisfied:
    dbus? ( gui )