diff --git a/src/www/minibar/pgf_online.js b/src/www/minibar/pgf_online.js
index ac6620ee5..b6329daba 100644
--- a/src/www/minibar/pgf_online.js
+++ b/src/www/minibar/pgf_online.js
@@ -5,48 +5,74 @@ function pgf_online(options) {
     var server = {
 	// State variables (private):
 	grammars_url: "/grammars/",
+	other_grammars_urls: [],
 	grammar_list: null,
 	current_grammar_url: null,
-	
+
 	// Methods:
 	switch_grammar: function(grammar_url,cont) {
  	    this.current_grammar_url=this.grammars_url+grammar_url;
 	    if(cont) cont();
 	},
-	get_grammarlist: function(cont) {
-	    http_get_json(this.grammars_url+"grammars.cgi",cont);
+	add_grammars_url: function(grammars_url,cont) {
+	    this.other_grammars_urls.push(grammars_url);
+	    if(cont) cont();
 	},
-	pgf_call: function(cmd,args,cont) {
+	switch_to_other_grammar: function(grammar_url,cont) {
+ 	    this.current_grammar_url=grammar_url;
+	    if(cont) cont();
+	},
+	get_grammarlist: function(cont,err) {
+	    if(this.grammar_list) cont(this.grammar_list)
+	    else http_get_json(this.grammars_url+"grammars.cgi",cont,err);
+	},
+	get_grammarlists: function(cont,err) { // May call cont several times!
+	    function pair(dir) {
+		return function(grammar_list){cont(dir,grammar_list)}
+	    }
+	    function ignore_error(err) { console.log(err) }
+	    this.get_grammarlist(pair(this.grammars_url),err)
+	    var ds=this.other_grammars_urls;
+	    for(var i in ds)
+		http_get_json(ds[i]+"grammars.cgi",pair(ds[i]),ignore_error);
+	},
+	pgf_call: function(cmd,args,cont,err) {
 	    var url=this.current_grammar_url+"?command="+cmd+encodeArgs(args)
-	    http_get_json(url,cont);
+	    http_get_json(url,cont,err);
 	},
 	
-	get_languages: function(cont) { this.pgf_call("grammar",{},cont); },
-	grammar_info: function(cont) { this.pgf_call("grammar",{},cont); },
+	get_languages: function(cont,err) {
+	    this.pgf_call("grammar",{},cont,err);
+	},
+	grammar_info: function(cont,err) {
+	    this.pgf_call("grammar",{},cont,err);
+	},
 	
-	get_random: function(args,cont) { // cat, limit
+	get_random: function(args,cont,err) { // cat, limit
 	    args.random=Math.random(); // side effect!!
-	    this.pgf_call("random",args,cont);
+	    this.pgf_call("random",args,cont,err);
 	},
-	linearize: function(args,cont) { // tree, to
-	    this.pgf_call("linearize",args,cont);
+	linearize: function(args,cont,err) { // tree, to
+	    this.pgf_call("linearize",args,cont,err);
 	},
-	complete: function(args,cont) { // from, input, cat, limit
-	    this.pgf_call("complete",args,cont);
+	complete: function(args,cont,err) { // from, input, cat, limit
+	    this.pgf_call("complete",args,cont,err);
 	},
-	parse: function(args,cont) { // from, input, cat
-	    this.pgf_call("parse",args,cont);
+	parse: function(args,cont,err) { // from, input, cat
+	    this.pgf_call("parse",args,cont,err);
 	},
-	translate: function(args,cont) { // from, input, cat, to
-	    this.pgf_call("translate",args,cont);
+	translate: function(args,cont,err) { // from, input, cat, to
+	    this.pgf_call("translate",args,cont,err);
 	},
-	translategroup: function(args,cont) { // from, input, cat, to
-	    this.pgf_call("translategroup",args,cont);
+	translategroup: function(args,cont,err) { // from, input, cat, to
+	    this.pgf_call("translategroup",args,cont,err);
+	},
+	browse: function(id,cont,err) {
+	    this.pgf_call("browse",{id:id,format:"json"},cont,err);
 	}
-	
     };
     for(var o in options) server[o]=options[o];
     if(server.grammar_list && server.grammar_list.length>0)
 	server.switch_grammar(server.grammar_list[0]);
     return server;
-}
\ No newline at end of file
+}
diff --git a/src/www/minibar/support.js b/src/www/minibar/support.js
index 08327d102..0e332a5c7 100644
--- a/src/www/minibar/support.js
+++ b/src/www/minibar/support.js
@@ -38,7 +38,7 @@ var json = {next:0};
 // Like jsonp, but instead of passing the name of the callback function, you 
 // pass the callback function directly, making it possible to use anonymous
 // functions.
-function jsonpf(url,callback)
+function jsonpf(url,callback,errorcallback)
 {
     var name="callback"+(json.next++);
     json[name]=function(x) { delete json[name]; callback(x); }
@@ -71,10 +71,12 @@ function ajax_http(method,url,body,callback,errorcallback) {
 	else alert(errortext)
     }
     else {
-	var statechange=function() {
+	function statechange() {
 	    if (http.readyState==4 || http.readyState=="complete") {
 		if(http.status<300) callback(http.responseText,http.status);
-		else if(errorcallback) errorcallback(http.responseText,http.status);
+		else if(errorcallback)
+		    errorcallback(http.responseText,http.status,
+				  http.getResponseHeader("Content-Type"));
 		else alert("Request for "+url+" failed: "
 			   +http.status+" "+http.statusText);
 	    }
@@ -96,8 +98,8 @@ function ajax_http_post(url,formdata,callback,errorcallback) {
 }
 
 // JSON via AJAX
-function ajax_http_get_json(url,cont) {
-    ajax_http_get(url,function(txt) { cont(eval("("+txt+")")); });
+function ajax_http_get_json(url,cont,errorcallback) {
+    ajax_http_get(url,function(txt){cont(eval("("+txt+")"));}, errorcallback);
 }
 
 function sameOrigin(url) {
@@ -107,9 +109,9 @@ function sameOrigin(url) {
 }
 
 // Use AJAX when possible, fallback to JSONP
-function http_get_json(url,cont) {
-    if(sameOrigin(url)) ajax_http_get_json(url,cont);
-    else jsonpf(url,cont);
+function http_get_json(url,cont,errorcallback) {
+    if(sameOrigin(url)) ajax_http_get_json(url,cont,errorcallback);
+    else jsonpf(url,cont,errorcallback);
 }
 
 /* --- URL construction ----------------------------------------------------- */