probably, the 4.8.4 FCKeditor provider default is set as static, but now the 4.9.0 default is set as dynamic, so we all need to set it back to static before you start modify our style list.
i just tried, put static and apply, but that's another problem that although i edit the fckstyle in the fckprovider folder ~\Providers\HtmlEditorProviders\Fck\FCKeditor\fckstyle.xml, that's nothing change in the style list.
When i use URL setting, copy a set xml and css to Root folder and select xml file and css file in the URL controller, it work exactly the same.
in this case of the static part, is it changed default location of the xml file?? or any bug? coz i already check the all config.js files, the default location is same as 4.8.4. whatever i edit the ~\Providers\HtmlEditorProviders\Fck\FCKeditor\fckstyle.xml, no changes happening. and also the css file in ~\Providers\HtmlEditorProviders\Fck\FCKeditor\editor\css\...
Thank you for the hints =)