Somewhat useless but cool none the less.

Can create a theme file that lets users change the color scheme for ServerSync.

Yeah could add some support for reading a custom theme config or something like that, I'll leave it as a backlog issue though as there are more pressing issues to solve around functionality and the current list of selectable themes is pretty good.

Since v4 offers a new user interface that supports themes, maybe now something can be done

In the code a theme is represented by:
BLUE_YELLOW ("-fx-primary : #232834; -fx-secondary : #edbe60; -fx-sidebar-primary: #1f2430; -fx-primarytext : #B2B2B2; -fx-secondarytext: #b6b6b6; -fx-background-color: -fx-primary;"),

The user will just have to suggest 5 colors.