nsIDOMNSHTMLDocument
te since gecko 14.0 domstring getselection(); nsidomdocument open(in acstring acontenttype, in boolean areplace); boolean querycommandenabled(in domstring commandid); boolean querycommandindeterm(in domstring commandid); boolean querycommandstate(in domstring commandid); boolean querycommandsupported(in domstring commandid); domstring querycommandtext(in domstring commandid); obsolete since gecko 14.0 domstring querycommandvalue(in domstring commandid); void releaseevents(in long eventflags); void routeevent(in nsidomevent evt); void write(); obsolete since gecko 2.0 void writeln(); obsolete since gecko 2.0 attributes attribute type description alinkcolor domstring ...
... commandid the name of the command to query.
...me of the command to query.

Document - Web APIs
commandshowhelp()obsolete since gecko 14 this method never did anything and always threw an exception, so it was removed in gecko 14.0 (firefox 14.0 / thunderbird 14.0 / seamonkey 2.11).