using LibreOffice since a long time i installed Language Tools for my texts (german and swiss german).
but your extension is not prepared for my high resolution laptop (surface) - the window and fonts are way too small.
please adapt your extension for the modern high resolution screens.
I didn’t find an easy way to fix this, and I’d have no way to test it anyway. You could try if using the current betas of Java 9 (final version to be released in a few months) help.