I just noticed that the LanguageTool extension(1) have some problems on both, the latest builds from the build bot and the one layer build from Jürgen, but it works without issues on 3.4.1 so it's not a problem with the extension but with AOO.
To test the problem, after installing the extension and restarting AOO type some text with grammar errors like a repeated word. The grammar error will be underlined with a blue wavy line on all versions, but if you right click on it you'll get suggestions only on 3.4.1, not on the 4.0 dev builds. Running the full spell and grammar check (F7) will work, only the context menu have problems and only for grammar errors: a right click over a spell error will show suggestions. I'm testing the 64 bits Linux builds. I did not fill an issue yet because I'm not sure which product do I need to use (extensions, Writer, lingucomponent, other?) (1) http://languagetool.org/ Regards Ricardo