After upgrading from 2.3.3 to 2.5 and then reactivating my TinyMCEAdvanced plugin, I went to Manage > Page and selected a page. In the wysiwyg editor, I found and clicked the "Kitchen Sink" button, but alas, not TinyMCEAdvanced icons appeared.
Furthermore, now I cannot get the Kitchen Sink button to appear.
I can get the TinyMCEAdvanced window to appear where I can select my toolbar icons, but they don't appear in WP's wysiwyg editor. Is this a problem with TinyMCEAdvanced and WP5 or just some bug in my system?
PS: Oops, looks like TinyMCEAdvanced version 2.2 (latest) is not compatible with WP2.5, at least that's the info at the TinyMCEAdvanced blogsite. I'll leave this post for others who might be interested.