On Windows 10, when executing the example extension using 'F5' and creating a new '.mydsl' file causes an exception while editing: "Request textDocument/hover failed. Message: Internal error, please look at the server's logs. Code: -32603". This is a complete show stopper for the example. A possible workaround is opening a folder and then creating the file there. I believe this has to do with the new 'no-folder-workspace' feature of VSCODE 1.9.1 (https://code.visualstudio.com/updates/v1_9#_debugging). This may also be a problem of the language-server implementation in xText/Eclipse.