The very big GH4 firmware update 2.0 has been released right now at http://panasonic.jp/support/global/cs/dsc/download/fts/index.html.
It contains many new features and fixes and to check them out download that pdf file: https://eww.pavc.panasonic.co.jp/support/en/dsc/fts/win/GH4_V20_ENG.pdf