Hi Daniel,
In principle, JTattoo still works with the latest version of BaseX and Java 11. However, we started assigning specific colors to some GUI components a while ago, as it turned out to be too tedious to achieve a unified look and feel (LAF) across various operating systems. As a result, only parts of the dark Hifi theme will be applied anymore. I imagine that the same problem may occur with alternative LAFs. We could certainly tweak that (e.g. by only using specific colors if the default LAF is used), but… Well, pull requests are welcome ;)
Personally, I also work with a dark background on Windows. I ended up with a lightweight tool that applies a color transformation to all pixels on the screen. It’s called Negative Screen [1], and it allows you to freely define the color transformation matrix.
Best,
Christian