This is a Chrome extension based on the open-source Mailvelope project. Once installed in Chrome, log in or refresh Gmail to see it in action. The script go-chrome.sh included with the source code will build both the transparent and opaque versions of the extension.
Our version of MP uses Python and Chromium Embedded Framework (which you must install first as dependencies) to display a web app which can be hosted on a remote server. The server code uses PHP and MySQL.