When attempting to build vlc with USE="skins -qt4", the following configuration error occurs: configure: error: The skins2 module depends on a the Qt4 development package. Without it you won't be able to open any dialog box from the interface, which makes the skins2 interface rather useless. Install the Qt4 development package or alternatively you can also configure with: --disable-qt4 --disable-skins2. This is despite the ebuild apparently disabling the skins USE flag. From what I can tell, this is because the vlc_use_needs() function only displays an ewarn about this, but doesn't actually disable the USE flag. Presumably the same problem occurs with the other usages of the vlc_use_needs() function. Building with USE="-skins -qt4" and USE="skins qt4" both work.
fixed now, thanks
