diff --git a/lib/x11/xcore.js b/lib/x11/xcore.js
index 61f4f81..b7cd750 100644
--- a/lib/x11/xcore.js
+++ b/lib/x11/xcore.js
@@ -59,7 +59,8 @@ function XClient(stream, displayNum, screenNum)
 
     this.rcrc_id = 0; // generated for each new resource
     this.seq_num = 0; // incremented in each request. (even if we don't expect reply)
-    
+    this.seq2stack = {}; // debug: map seq_num to stack at the moment request was issued   
+ 
     // in/out packets indexed by sequence ID
     //this.requests = {};
     this.replies = {};
@@ -104,6 +105,12 @@ XClient.prototype.importRequestsFromTemplates = function(target, reqs)
         target[r] = (function(reqName) {              
             var reqFunc = function req_proxy() {
             client.seq_num++; // TODO: handle overflow (seq should be last 15 (?)  bits of the number
+
+            var err = new Error;
+            err.name = r;
+            Error.captureStackTrace(err, arguments.callee);
+            client.seq2stack[client.seq_num] = err.stack;
+
             // is it fast?
             var args = Array.prototype.slice.call(req_proxy.arguments);
 
@@ -221,9 +228,10 @@ XClient.prototype.expectReplyHeader = function()
             {              
                 var error_code = res[1];
                 var error = {};
-                error.code = error_code;
+                error.error = error_code;
                 error.seq = seq_num;
                 error.message = xerrors.errorText[error_code];
+                error.stack = client.seq2stack[error.seq]
 
                 // unpack error packet (32 bytes for all error types, 8 of them in CCSL header)
                 client.pack_stream.get(24, function(buf) {
@@ -240,6 +248,9 @@ XClient.prototype.expectReplyHeader = function()
                     if (handler) {
                         var callback = handler[1];
                         callback(error);
+                        if (!error.handled)
+                            client.emit('error', error);
+                        delete client.seq2stack[seq_num];
                         delete client.replies[seq_num];
                     } else
                         client.emit('error', error);