WP ui not available on the editor

I believe that problem is because the plugin hasn’t been updated for a couple of years and it now doesn’t work well with the newer versions of WordPress. You should be able to get some functionality by working on the Text side of the editor where the tab and wrap buttons are still present, but you probably can add posts, pages, dialogs or other features it used to support.

The loss is a shame since the plugin is pretty cool.