public static void initialize() {
		if (INSTANCE instanceof ApplicationThemeManager) {
			Msg.error(ApplicationThemeManager.class,
				"Attempted to initialize theming more than once!");
			return;
		}

		ApplicationThemeManager themeManager = new ApplicationThemeManager();
		themeManager.doInitialize();
	}
Initialized the Theme and its values for the application.
Ghidra/Framework/Gui/src/main/java/generic/theme/ApplicationThemeManager.java