Create custom base ui theme

[tobiasdiez]

Currently, we use the built-in JavaFX theme "Modena" as the base and overwrite certain styles. In some cases this is a bit problematic and it would be better to copy modena.css and make our changes directly to this file.
The new base UI css file can be registered using https://docs.oracle.com/javase/8/javafx/api/javafx/application/Application.html#setUserAgentStylesheet-java.lang.String-

[Siedlerchr]

I guess with our DarkTheme and the LightTheme this issue is now obsolete.

[tobiasdiez]

Nope, the Base.css is applied on top of Modena. Since we have many changes, it would be worthwhile to completely replace Modena by our base css.

[Siedlerchr]

I'm against copying modena. If there are updates to Javafx we would always need to re copy the whole stuff.
it might be better using https://github.com/mkpaz/atlantafx