Added a copy of Firebug Lite for debugging purposes. License is uncertain but being treated as MPL. (If is is not MPL then it is under something more permissive that permits relicensing anyway)
tinyMCE.addI18n('en.xhtmlxtras_dlg',{
attribute_label_title:"Title",
attribute_label_id:"ID",
attribute_label_class:"Class",
attribute_label_style:"Style",
attribute_label_cite:"Cite",
attribute_label_datetime:"Date/Time",
attribute_label_langdir:"Text Direction",
attribute_option_ltr:"Left to right",
attribute_option_rtl:"Right to left",
attribute_label_langcode:"Language",
attribute_label_tabindex:"TabIndex",
attribute_label_accesskey:"AccessKey",
attribute_events_tab:"Events",
attribute_attrib_tab:"Attributes",
general_tab:"General",
attrib_tab:"Attributes",
events_tab:"Events",
fieldset_general_tab:"General Settings",
fieldset_attrib_tab:"Element Attributes",
fieldset_events_tab:"Element Events",
title_ins_element:"Insertion Element",
title_del_element:"Deletion Element",
title_acronym_element:"Acronym Element",
title_abbr_element:"Abbreviation Element",
title_cite_element:"Citation Element",
remove:"Remove",
insert_date:"Insert current date/time",
option_ltr:"Left to right",
option_rtl:"Right to left",
attribs_title:"Insert/Edit Attributes"
});