WE have also experienced after upgrade to 3.4.2 that the our custom users page that uses tinymce editor from wordpress does not display it’s toolbars.
After some review with our website I found out that the error causing this was the import url at wp-includes\js\tinymce\themes\advanced\skins\wp_theme\ui.css
which is @import url(“../../../../../../css/editor-buttons.css?ver=20111114”);
it lacks 1 “../” and the also you need to use editor.css instead of editor-buttons.css
the import line should now look like this
@import url(“../../../../../../../css/editor.css?ver=20111114”);
after updating the file the editor’s toolbar was fix.
HTH
Regards,
Joeven