diff --git a/demo/app.js b/demo/app.js
index ae2513c1..65eebf47 100644
--- a/demo/app.js
+++ b/demo/app.js
@@ -21,6 +21,10 @@ app.get('/main.js', function(req, res){
   res.sendFile(__dirname + '/main.js');
 });
 
+app.get('/js/*.js', function(req, res){
+    res.sendFile(__dirname + req.url);
+});
+
 const SHELL_ARGS = {
     bash: ['--login'],
     'cmd.exe': [],
diff --git a/demo/index.html b/demo/index.html
index b2f64669..494b9f38 100644
--- a/demo/index.html
+++ b/demo/index.html
@@ -10,7 +10,7 @@
         <script src="/build/xterm.js" ></script>
 
         <script src="/build/addons/attach/attach.js" ></script>
-        <script src="/build/addons/zmodem/zmodemjs/dist/zmodem.js" ></script>
+        <script src="/js/zmodem.devel.js" ></script>
         <script src="/build/addons/zmodem/zmodem.js" ></script>
 
         <script src="/build/addons/fit/fit.js" ></script>
@@ -57,7 +57,7 @@
 
             <form id="zm_progress" style="display: none" action="javascript:void(0)">
                 <div><span id="percent_received"></span>% (<span id="bytes_received"></span> bytes) received</div>
-                <button type="button" onclick="abort_current_session(); this.form.style.display='none';">Abort ZMODEM</button>
+                <button id="zm_progress_skipper" type="button" onclick="skip_current_file();">Skip File</button>
             </form>
 
             <form id="zm_choose" style="display: none" action="javascript:void(0)">
@@ -123,7 +123,7 @@
           </div>
         </div>
         <p><strong>Attention:</strong> The demo is a barebones implementation and is designed for xterm.js evaluation purposes only. Exposing the demo to the public as is would introduce security risks for the host.</p>
-        <p><sup>*</sup> ZMODEM file transfers are supported via an addon. To try it out, install <a href="https://ohse.de/uwe/software/lrzsz.html"><code>lrzsz</code></a> onto the remote peer, then type <code>rz</code> to send from your browser or <code>sz &lt;file&gt;</code> to send from the remote peer.</p>
+        <p><sup>*</sup> ZMODEM file transfers are supported via an addon. To try it out, install <a href="https://ohse.de/uwe/software/lrzsz.html"><code>lrzsz</code></a> onto the remote peer, then run <code>rz</code> to send from your browser or <code>sz &lt;file&gt;</code> to send from the remote peer.</p>
         <script src="main.js" defer ></script>
     </body>
 </html>
diff --git a/demo/js/zmodem.devel.js b/demo/js/zmodem.devel.js
new file mode 120000
index 00000000..7c1732ee
--- /dev/null
+++ b/demo/js/zmodem.devel.js
@@ -0,0 +1 @@
+../../node_modules/zmodem.js/dist/zmodem.devel.js
\ No newline at end of file
diff --git a/demo/js/zmodem.js b/demo/js/zmodem.js
new file mode 120000
index 00000000..88c4a96d
--- /dev/null
+++ b/demo/js/zmodem.js
@@ -0,0 +1 @@
+../../node_modules/zmodem.js/dist/zmodem.js
\ No newline at end of file
diff --git a/demo/main.js b/demo/main.js
index 703658c4..522436cf 100644
--- a/demo/main.js
+++ b/demo/main.js
@@ -121,23 +121,21 @@ function createTerminal() {
 
         term.on("zmodemDetect", (detection) => {
             function do_zmodem() {
-                try {
-                    term.detach();
-                    let zsession = detection.confirm();
+                term.detach();
+                let zsession = detection.confirm();
 
-                    current_zsession = zsession;
+                var promise;
 
-                    if (zsession.type === "receive") {
-                        _handle_receive_session(zsession);
-                    }
-                    else {
-                        _handle_send_session(zsession);
-                    }
+                if (zsession.type === "receive") {
+                    promise = _handle_receive_session(zsession);
                 }
-                catch(e) { throw e }
-                finally {
+                else {
+                    promise = _handle_send_session(zsession);
+                }
+
+                promise.catch( console.error.bind(console) ).then( () => {
                     term.attach(socket);
-                }
+                } );
             }
 
             if (_auto_zmodem()) {
@@ -191,15 +189,26 @@ function _save_to_disk(xfer, buffer) {
     return Zmodem.Browser.save_to_disk(buffer, xfer.get_details().name);
 }
 
-function _update_progress(xfer) {
-    document.getElementById("zm_progress").style.display = "";
+var skipper_button = document.getElementById("zm_progress_skipper");
+var skipper_button_orig_text = skipper_button.textContent;
 
+function _show_progress() {
+    skipper_button.disabled = false;
+    skipper_button.textContent = skipper_button_orig_text;
+
+    document.getElementById("bytes_received").textContent = 0;
+    document.getElementById("percent_received").textContent = 0;
+
+    document.getElementById("zm_progress").style.display = "";
+}
+
+function _update_progress(xfer) {
     var total_in = xfer.get_offset();
 
     document.getElementById("bytes_received").textContent = total_in;
 
     var percent_received = 100 * total_in / xfer.get_details().size;
-    document.getElementById("percent_received").textContent = percent_received;
+    document.getElementById("percent_received").textContent = percent_received.toFixed(2);
 }
 
 function _hide_progress() {
@@ -217,6 +226,8 @@ function _auto_zmodem() {
 
 function _handle_receive_session(zsession) {
     zsession.on("offer", function(xfer) {
+        current_receive_xfer = xfer;
+
         _show_file_info(xfer);
 
         var offer_form = document.getElementById("zm_offer");
@@ -226,7 +237,9 @@ function _handle_receive_session(zsession) {
 
             //START
             //if (offer_form.zmaccept.value) {
-            if (document.getElementById("zmaccept_yes").checked) {
+            if (_auto_zmodem() || document.getElementById("zmaccept_yes").checked) {
+                _show_progress();
+
                 var FILE_BUFFER = [];
                 xfer.on("input", (payload) => {
                     _update_progress(xfer);
@@ -254,54 +267,69 @@ function _handle_receive_session(zsession) {
         }
     } );
 
-    zsession.on("session_end", () => {
-        _hide_file_info();
-        _hide_progress();
+    var promise = new Promise( (res) => {
+        zsession.on("session_end", () => {
+            _hide_file_info();
+            _hide_progress();
+            res();
+        } );
     } );
 
     zsession.start();
+
+    return promise;
 }
 
 function _handle_send_session(zsession) {
     var choose_form = document.getElementById("zm_choose");
     choose_form.style.display = "";
-    choose_form.onsubmit = function(e) {
-        choose_form.style.display = "none";
 
-        var file_el = document.getElementById("zm_files");
-        var files_obj = file_el.files;
+    var promise = new Promise( (res) => {
+        choose_form.onsubmit = function(e) {
+            choose_form.style.display = "none";
 
-        Zmodem.Browser.send_files(
-            zsession,
-            files_obj,
-            {
-                on_offer_response(obj, xfer) {
-                    //console.log("offer", xfer ? "accepted" : "skipped");
-                },
-                on_progress(obj, xfer) {
-                    _update_progress(xfer);
-                },
-                on_file_complete(obj) {
-                    //console.log("COMPLETE", obj);
-                    _hide_progress();
-                },
-            }
-        ).then(_hide_progress).then(
-            zsession.close.bind(zsession),
-            console.error.bind(console)
-        ).then( () => {
-            _hide_file_info();
-            _hide_progress();
-        } );
-    };
+            var file_el = document.getElementById("zm_files");
+            var files_obj = file_el.files;
+
+            Zmodem.Browser.send_files(
+                zsession,
+                files_obj,
+                {
+                    on_offer_response(obj, xfer) {
+                        if (xfer) _show_progress();
+                        //console.log("offer", xfer ? "accepted" : "skipped");
+                    },
+                    on_progress(obj, xfer) {
+                        _update_progress(xfer);
+                    },
+                    on_file_complete(obj) {
+                        //console.log("COMPLETE", obj);
+                        _hide_progress();
+                    },
+                }
+            ).then(_hide_progress).then(
+                zsession.close.bind(zsession),
+                console.error.bind(console)
+            ).then( () => {
+                _hide_file_info();
+                _hide_progress();
+                res();
+            } );
+        };
+    } );
+
+    return promise;
 }
 
 //This is here to allow canceling of an in-progress ZMODEM transfer.
-var current_zsession;
+var current_receive_xfer;
 
 //Called from HTML directly.
-function abort_current_session() {
-    current_zsession.abort();
+function skip_current_file() {
+    current_receive_xfer.skip();
+
+    skipper_button.disabled = true;
+    skipper_button.textContent = "Waiting for server to acknowledge skip …";
 }
 
 function runRealTerminal() {