diff --git a/android/tinySSB/app/build.gradle b/android/tinySSB/app/build.gradle
index fa7bb93..021680d 100644
--- a/android/tinySSB/app/build.gradle
+++ b/android/tinySSB/app/build.gradle
@@ -5,7 +5,6 @@ apply plugin: 'kotlin-kapt'
 android {
     namespace "tremolavossbol"
     compileSdk 30
-    buildToolsVersion "30.0.3"
 
     buildFeatures {
         viewBinding = true
@@ -13,7 +12,7 @@ android {
 
     defaultConfig {
         applicationId "nz.scuttlebutt.tremolavossbol"
-        minSdkVersion 26
+        minSdk 24
         targetSdkVersion 30
         versionCode 1
         versionName "0.1"
diff --git a/android/tinySSB/app/src/main/assets/web/bipf.js b/android/tinySSB/app/src/main/assets/web/bipf.js
index 4ffeecb..ecda72c 100644
--- a/android/tinySSB/app/src/main/assets/web/bipf.js
+++ b/android/tinySSB/app/src/main/assets/web/bipf.js
@@ -41,7 +41,13 @@ const BIPF_MATH_POW_5 = Math.pow(2, 5*7)
 const BIPF_MATH_POW_6 = Math.pow(2, 6*7)
 const BIPF_MATH_POW_7 = Math.pow(2, 7*7)
 
-function bipf_fvdecode(buf, offset) {
+function unzigzag(value) {
+  let s = value & 0x01;
+  value >>>= 1;
+  return s ? -value - 1 : value
+}
+
+function bipf_fvdecode(buf, offset, zigzag) {
   offset = offset || 0
 
   buf = new Uint8Array(buf)
@@ -51,56 +57,56 @@ function bipf_fvdecode(buf, offset) {
   res += b & BIPF_REST
   if (b < BIPF_MSB) {
     bipf_fvdecode.bytes = 1
-    return res
+    return zigzag ? unzigzag(res) : res
   }
 
   b = buf[offset + 1]
   res += (b & BIPF_REST) << 7
   if (b < BIPF_MSB) {
     bipf_fvdecode.bytes = 2
-    return res
+    return zigzag ? unzigzag(res) : res
   }
 
   b = buf[offset + 2]
   res += (b & BIPF_REST) << 14
   if (b < BIPF_MSB) {
     bipf_fvdecode.bytes = 3
-    return res
+    return zigzag ? unzigzag(res) : res
   }
 
   b = buf[offset + 3]
   res += (b & BIPF_REST) << 21
   if (b < BIPF_MSB) {
     bipf_fvdecode.bytes = 4
-    return res
+    return zigzag ? unzigzag(res) : res
   }
 
   b = buf[offset + 4]
   res += (b & BIPF_REST) * BIPF_MATH_POW_4
   if (b < BIPF_MSB) {
     bipf_fvdecode.bytes = 5
-    return res
+    return zigzag ? unzigzag(res) : res
   }
 
   b = buf[offset + 5]
   res += (b & BIPF_REST) * BIPF_MATH_POW_5
   if (b < BIPF_MSB) {
     bipf_fvdecode.bytes = 6
-    return res
+    return zigzag ? unzigzag(res) : res
   }
 
   b = buf[offset + 6]
   res += (b & BIPF_REST) * BIPF_MATH_POW_6
   if (b < BIPF_MSB) {
     bipf_fvdecode.bytes = 7
-    return res
+    return zigzag ? unzigzag(res) : res
   }
 
   b = buf[offset + 7]
   res += (b & BIPF_REST) * BIPF_MATH_POW_7
   if (b < BIPF_MSB) {
     bipf_fvdecode.bytes = 8
-    return res
+    return zigzag ? unzigzag(res) : res
   }
 
   bipf_fvdecode.bytes = 0
@@ -110,11 +116,13 @@ function bipf_fvdecode(buf, offset) {
 var BIPF_MSBALL = ~BIPF_REST
 var BIPF_INT31 = Math.pow(2, 31)
 
-function bipf_fvencode(num, out, offset) {
+function bipf_fvencode(num, out, offset, zigzag) {
   if (Number.MAX_SAFE_INTEGER && num > Number.MAX_SAFE_INTEGER) {
     bipf_fvencode.bytes = 0
     throw new RangeError('Could not encode varint')
   }
+  if (zigzag)
+    num = num >= 0 ? 2*num : (2 * -num) - 1 // zig-zag encoding of sign
   // out = out || []
   out = new Uint8Array(out)
   offset = offset || 0
@@ -145,21 +153,21 @@ var BIFP_N7 = Math.pow(2, 49)
 var BIFP_N8 = Math.pow(2, 56)
 var BIFP_N9 = Math.pow(2, 63)
 
-function bipf_fvencodingLength (value) {
-  if (value >= 0)
-      return (
-          value < BIFP_N1 ? 1
-              : value < BIFP_N2 ? 2
-                  : value < BIFP_N3 ? 3
-                      : value < BIFP_N4 ? 4
-                          : value < BIFP_N5 ? 5
-                              : value < BIFP_N6 ? 6
-                                  : value < BIFP_N7 ? 7
-                                      : value < BIFP_N8 ? 8
-                                          : value < BIFP_N9 ? 9
-                                              :              10
-      )
-  return -1 // FIXME: handle negative numbers
+function bipf_fvencodingLength (value, zigzag) {
+  if (zigzag)
+    value = value >= 0 ? 2*value : (2 * -value) - 1 // zig-zag encoding of sign
+  return (
+      value < BIFP_N1 ? 1
+          : value < BIFP_N2 ? 2
+              : value < BIFP_N3 ? 3
+                  : value < BIFP_N4 ? 4
+                      : value < BIFP_N5 ? 5
+                          : value < BIFP_N6 ? 6
+                              : value < BIFP_N7 ? 7
+                                  : value < BIFP_N8 ? 8
+                                      : value < BIFP_N9 ? 9
+                                          :              10
+  )
 }
 
 // --- encode
@@ -177,9 +185,12 @@ const BIPF_encoders = [
     return b.length
   },
   function Integer(i, buffer, start) {
-    let dv = new DataView(buffer);
-    dv.setInt32(start, i, true);
-    return 4
+    // let dv = new DataView(buffer);
+    // dv.setInt32(start, i, true);
+    // return 4
+    bipf_fvencode(i, buffer, start, true);
+    return bipf_fvencode.bytes;
+
   },
   function Double(d, buffer, start) {
     let dv = new DataView(buffer);
@@ -216,20 +227,20 @@ const BIPF_encodingLengthers = [
     return b.length
   },
   function Integer(i) {
-    // return bipf_fvencodingLength(i)
-    return 4
+    // return 4
+    return bipf_fvencodingLength(i, true);
   },
   function Double(d) {
     return 8
   },
   function Array(a) {
     var bytes = 0
-    for (var i = 0; i < a.length; i++) bytes += bipf_encodingLength(a[i])
+    for (var i = 0; i < a.length; i++) bytes += bipf_encodingLength(a[i], false)
     return bytes
   },
   function Object(o) {
     var bytes = 0
-    for (var k in o) bytes += bipf_encodingLength(k) + bipf_encodingLength(o[k])
+    for (var k in o) bytes += bipf_encodingLength(k) + bipf_encodingLength(o[k], false)
     return bytes
   },
   function boolnull(b, buffer, start) {
@@ -258,7 +269,7 @@ function bipf_encodingLength(value) {
   if (type === void 0) throw new Error('unknown type: ' + JSON.stringify(value))
   if (type === BIPF_ALREADY_BIPF) return value.length
   const len = BIPF_encodingLengthers[type](value)
-  return bipf_fvencodingLength(len << BIPF_TAG_SIZE) + len
+  return bipf_fvencodingLength(len << BIPF_TAG_SIZE, false) + len
 }
 
 function bipf_encode(value, buffer, start, _len) {
@@ -273,7 +284,7 @@ function bipf_encode(value, buffer, start, _len) {
   //  if(!buffer)
   //    buffer = Buffer.allocUnsafe(len)
   //throw new Error('buffer must be provided')
-  bipf_fvencode((len << BIPF_TAG_SIZE) | type, buffer, start)
+  bipf_fvencode((len << BIPF_TAG_SIZE) | type, buffer, start, false)
   const bytes = bipf_fvencode.bytes
   return BIPF_encoders[type](value, buffer, start + bytes) + bytes
 }
@@ -294,22 +305,22 @@ function bipf_isIdempotent(buffer) {
 }
 
 function bipf_getEncodedLength(buffer, start) {
-  return bipf_fvdecode(buffer, start) >> BIPF_TAG_SIZE
+  return bipf_fvdecode(buffer, start, false) >> BIPF_TAG_SIZE
 }
 
 function bipf_getEncodedType(buffer, start) {
-  return bipf_fvdecode(buffer, start) & BIPF_TAG_MASK
+  return bipf_fvdecode(buffer, start, false) & BIPF_TAG_MASK
 }
 
 function bipf_allocAndEncode(value) {
-  const len = bipf_encodingLength(value)
+  const len = bipf_encodingLength(value, false)
   const buffer = Buffer.allocUnsafe(len)
   bipf_encode(value, buffer, 0)
   return buffer
 }
 
 function bipf_allocAndEncodeIdempotent(value) {
-  const len = bipf_encodingLength(value)
+  const len = bipf_encodingLength(value, false)
   const buffer = Buffer.allocUnsafe(len)
   bipf_encodeIdempotent(value, buffer, 0)
   return buffer
@@ -327,8 +338,9 @@ function bipf_decodeBuffer(buffer, start, length) {
 }
 
 function bipf_decodeInteger(buf, start, length) {
-  let dv = new DataView(buf);
-  return dv.getInt32(start, true); //TODO: encode in minimum bytes
+  // let dv = new DataView(buf);
+  // return dv.getInt32(start, true); //TODO: encode in minimum bytes
+  return bipf_fvdecode(buf, start, true);
 }
 
 function bipf_decodeDouble(buffer, start, length) {
@@ -339,7 +351,7 @@ function bipf_decodeDouble(buffer, start, length) {
 function bipf_decodeArray(buffer, start, length) {
   const a = []
   for (let c = 0; c < length; ) {
-    const tag = bipf_fvdecode(buffer, start + c)
+    const tag = bipf_fvdecode(buffer, start + c, false)
     const type = tag & BIPF_TAG_MASK
     if (type === 7) throw new Error('reserved type')
     const len = tag >> BIPF_TAG_SIZE
@@ -354,7 +366,7 @@ function bipf_decodeArray(buffer, start, length) {
 function bipf_decodeObject(buffer, start, length) {
   const o = {}
   for (let c = 0; c < length; ) {
-    const tag = bipf_fvdecode(buffer, start + c)
+    const tag = bipf_fvdecode(buffer, start + c, false)
     // JavaScript only allows string-valued and Symbol keys for objects
     if (tag & BIPF_TAG_MASK) throw new Error('required type:string')
     const len = tag >> BIPF_TAG_SIZE
@@ -362,7 +374,7 @@ function bipf_decodeObject(buffer, start, length) {
     const key = bipf_decodeString(buffer, start + c, len)
     c += len
 
-    const tag2 = bipf_fvdecode(buffer, start + c)
+    const tag2 = bipf_fvdecode(buffer, start + c, false)
     const type2 = tag2 & BIPF_TAG_MASK
     if (type2 === 7) throw new Error('reserved type:value')
     const len2 = tag2 >> BIPF_TAG_SIZE
@@ -404,7 +416,7 @@ function bipf_decodeType(type, buffer, start, len) {
 
 function bipf_decode(buffer, start) {
   start = start | 0
-  const tag = bipf_fvdecode(buffer, start)
+  const tag = bipf_fvdecode(buffer, start, false)
   const type = tag & BIPF_TAG_MASK
   const len = tag >> BIPF_TAG_SIZE
   const bytes = bipf_fvdecode.bytes
@@ -444,7 +456,7 @@ const isObject = (object) => {
 }
 
 function testEncodeDecode(value) {
-    const buf = new ArrayBuffer(bipf_encodingLength(value))
+    const buf = new ArrayBuffer(bipf_encodingLength(value, false))
     const len = bipf_encode(value, buf, 0)
     console.log('in:', JSON.stringify(value), '--> encoded:', buf.slice(0, len))
     //''+jsonString to get 'undefined' string.
@@ -491,9 +503,11 @@ pkg = {
 }
 
 testEncodeDecode(100)
+testEncodeDecode(63)
 testEncodeDecode(0)
 testEncodeDecode(1)
 testEncodeDecode(-1)
+testEncodeDecode(-63)
 testEncodeDecode(-100)
 testEncodeDecode(123.456)
 testEncodeDecode(2147483647)
@@ -514,7 +528,6 @@ testEncodeDecode({ foo: true })
 // testEncodeDecode([-1, { foo: true }, Buffer.from('deadbeef', 'hex')])
 testEncodeDecode(pkg)
 testEncodeDecode({ 1: true })
-
 */
 
 // eof
diff --git a/android/tinySSB/app/src/main/assets/web/img/pencil.png b/android/tinySSB/app/src/main/assets/web/img/pencil.png
new file mode 100644
index 0000000..6f74cff
Binary files /dev/null and b/android/tinySSB/app/src/main/assets/web/img/pencil.png differ
diff --git a/android/tinySSB/app/src/main/assets/web/sketch.js b/android/tinySSB/app/src/main/assets/web/sketch.js
index 1c69613..10b31b5 100644
--- a/android/tinySSB/app/src/main/assets/web/sketch.js
+++ b/android/tinySSB/app/src/main/assets/web/sketch.js
@@ -33,7 +33,10 @@ function chat_openSketch() {
     canvas.style.left = '0';
     canvas.width = window.innerWidth; // Full screen width
     canvas.height = window.innerHeight; // Full screen height
-
+    /* on API 26, the canvas is not showing. Perhaps
+      https://stackoverflow.com/questions/24586530/android-canvas-drawing-not-visible#24586531
+    canvas.drawARGB(0, 225, 225, 255);
+    */
     canvas.style.backgroundColor = '#ffffff';
     document.body.appendChild(canvas);
 
@@ -63,13 +66,16 @@ function chat_openSketch() {
     // Create a close button and style it
     let closeButton = document.createElement('button');
     closeButton.id = 'btn:closeSketch';
-    closeButton.innerHTML = 'Cancel';
+    // closeButton.innerHTML = 'Cancel';
+    closeButton.style['background-image'] = "url('img/cancel.svg')"
     closeButton.style.position = 'fixed';
     closeButton.style.top = '10px';
     closeButton.style.right = '10px';
+    closeButton.style.width= '40px';
+    closeButton.style.height = '40px';
     closeButton.style.padding = '10px';
     closeButton.style.backgroundColor = '#ff0000';
-    closeButton.style.color = '#ffffff';
+    // closeButton.style.color = '#ffffff';
     closeButton.style.border = 'none';
     closeButton.style.borderRadius = '5px';
     closeButton.style.cursor = 'pointer';
@@ -79,13 +85,16 @@ function chat_openSketch() {
     // Do the same with a submit button
     let submitButton = document.createElement('button');
     submitButton.id = 'btn:submitSketch';
-    submitButton.innerHTML = 'Submit';
+    // submitButton.innerHTML = 'Submit';
+    submitButton.style['background-image'] = "url('img/checked.svg')"
     submitButton.style.position = 'fixed';
     submitButton.style.top = '10px';
-    submitButton.style.right = '100px';
+    submitButton.style.right = '55px';
+    submitButton.style.width= '40px';
+    submitButton.style.height = '40px';
     submitButton.style.padding = '10px';
     submitButton.style.backgroundColor = '#008000';
-    submitButton.style.color = '#ffffff';
+    // submitButton.style.color = '#ffffff';
     submitButton.style.border = 'none';
     submitButton.style.borderRadius = '5px';
     submitButton.style.cursor = 'pointer';
@@ -132,7 +141,7 @@ function chat_openSketch() {
     document.body.appendChild(colorChoiceButton);
 
     //Array of colors we want to include
-    var sketch_colors = ['#000000', '#ff0000', '#00ff00', '#0000ff', '#ffff00', '#ff00ff'];
+    var sketch_colors = ['#000000', '#ee0000', '#00aa00', '#4040ff', '#ffee00', '#ff00ff'];
 
     // Add color buttons to the color palette
     Array.from(Array(sketch_colors.length).keys()).forEach(function(ndx) {
@@ -231,12 +240,16 @@ function chat_openSketch() {
         [sketch.lastX, sketch.lastY] = [Math.round(e.touches[0].clientX - rect.left),
                                         Math.round(e.touches[0].clientY - rect.top)];
         sketch.svg.push(['p',sketch.lastX,sketch.lastY])
+        sketch.start = Date.now()
     }
 
 
     //Function when users move their finger to continue drawing
     function draw(e) {
         if (!sketch.isDrawing) return;
+        let t = Date.now()
+        if (t - sketch.start < 35) return;
+        sketch.start = t;
         e.preventDefault();
         let rect = e.target.getBoundingClientRect();
         let ctx_ = sketch.ctx;
@@ -384,8 +397,12 @@ function chat_closeSketch() {
   if (undoButton) {
       undoButton.parentNode.removeChild(undoButton);
   }
+
+  sketch.svg = []
+  sketch.currSize = 0;
 }
 
+/*
 function sketch_reduceResolution(base64String, reductionFactor) {
     return new Promise((resolve, reject) => {
         const img = new Image();
@@ -411,6 +428,7 @@ function sketch_reduceResolution(base64String, reductionFactor) {
         };
       });
 }
+*/
 
 // returns the size of the base64 string that represents the sketch
 async function sketch_get_current_size() {
diff --git a/android/tinySSB/app/src/main/assets/web/tremola.html b/android/tinySSB/app/src/main/assets/web/tremola.html
index f5a41f3..0a07c9e 100644
--- a/android/tinySSB/app/src/main/assets/web/tremola.html
+++ b/android/tinySSB/app/src/main/assets/web/tremola.html
@@ -360,7 +360,7 @@
 
         <p>MIT License for tinySSB (previously known as tinyTremola and VoSSBoL)
 
-        <p>Copyright (c) 2021-23 Computer Networks Group, University of Basel
+        <p>Copyright (c) 2021-24 Computer Networks Group, University of Basel
 
         <p>Permission is hereby granted, free of charge, to any person obtaining a copy
           of this software and associated documentation files (the "Software"), to deal
@@ -548,7 +548,8 @@
         <div style="position: relative;">
 
         <textarea id='draft' rows=3 placeholder='Tap here to type' style="padding-right: 40px;"></textarea>
-        <button id="attachmentButton" onclick="chat_open_attachments_menu()" class="flat buttontext img-gray-filter" style="background-image: url('img/paperclip.svg'); background-color: transparent; width: 35px; height: 35px; position: absolute; right: 2px; top: 46%; transform: translateY(-50%);"></button>
+        <!-- ('img/paperclip.svg') class="flat buttontext img-gray-filter" -->
+        <button id="attachmentButton" onclick="chat_open_attachments_menu()" class="flat buttontext" style="background-image: url('img/pencil.png'); background-color: transparent; width: 40px; height: 40px; position: absolute; right: 2px; top: 46%; transform: translateY(-50%);"></button>
         </div>
       <!-- td width=5% height=100%><button id='btn:attach' class="flat passive buttontext"><font size=+2>&#x1F4CE;</font><br><font size=small>Attach</font></button></td -->
       <td width=8% height=100%><button id='btn:attach' class="flat white buttontext" onclick="btnBridge(this);" style="background-image: url('img/record.svg'); fill: #fff; width: 50px; height: 50px; margin-bottom: 4px;"></button>
diff --git a/android/tinySSB/app/src/main/assets/web/tremola.js b/android/tinySSB/app/src/main/assets/web/tremola.js
index f15aa83..ceb8274 100644
--- a/android/tinySSB/app/src/main/assets/web/tremola.js
+++ b/android/tinySSB/app/src/main/assets/web/tremola.js
@@ -383,34 +383,42 @@ function load_post_item(p) { // { 'key', 'from', 'when', 'body', 'to' (if group
             var ui8 = new Uint8Array(buf);
             for (var i = 0; i < binStr.length; i++)
                ui8[i] = binStr.charCodeAt(i);
-            let img = bipf_decode(buf, 0);
-            // console.log('got svg', JSON.stringify(img));
-            // img[0] -- version of this svg encoding, currently 1, ignored
-            if (Number.isInteger(img[0]))
-              img = img.slice(1)
-            var svg = `<svg version="1.1" width="${img[0][1]}" height="${img[0][2]}"`
-            svg += ' style="background-color:white" xmlns="http://www.w3.org/2000/svg">'
-            svg += '<g stroke-linecap="round" fill="none">'
-            let coltab = ['#ffffff', '#000000', '#ff0000', '#00ff00', '#0000ff', '#ffff00', '#ff00ff'];
-            let widtab = [2, 5, 10, 30];
-            var colNdx = 0;
-            var widNdx = 0;
-            img.slice(1).forEach((e) => {
-              if (e[0] == 'c') {
-                colNdx = e[1];
-              } else if (e[0] == 'w') {
-                widNdx = e[1];
-              } else if (e[0] == 'p') {
-                svg += `<path d="M ${e[1]} ${e[2]} l`
-                e.slice(3).forEach((i) => {
-                  svg += ` ${i}`
-                })
-                svg += `" stroke="${coltab[colNdx+1]}" stroke-width="${widtab[widNdx]}"/>`
-              }
-            })
-            svg += '</g></svg>'
-            // console.log('svg:', svg)
-            box += `<img src="data:image/svg+xml;base64,${btoa(svg)}"`;
+            var src;
+            try {
+               let img = bipf_decode(buf, 0);
+               // console.log('got svg', JSON.stringify(img));
+               // img[0] -- version of this svg encoding, currently 1, ignored
+               if (Number.isInteger(img[0]))
+                 img = img.slice(1)
+               var svg = `<svg version="1.1" width="${img[0][1]}" height="${img[0][2]}"`
+               svg += ' style="background-color:white" xmlns="http://www.w3.org/2000/svg">'
+               svg += '<g stroke-linecap="round" fill="none">'
+               let coltab = ['#ffffff', '#000000', '#ee0000', '#00aa00', '#4040ff', '#ffee00', '#ff00ff'];
+               // let coltab = ['#ffffff', '#000000', '#ff0000', '#00ff00', '#0000ff', '#ffff00', '#ff00ff'];
+               let widtab = [2, 5, 10, 30];
+               var colNdx = 0;
+               var widNdx = 0;
+               img.slice(1).forEach((e) => {
+                 if (e[0] == 'c') {
+                   colNdx = e[1];
+                 } else if (e[0] == 'w') {
+                   widNdx = e[1];
+                 } else if (e[0] == 'p') {
+                   svg += `<path d="M ${e[1]} ${e[2]} l`
+                   e.slice(3).forEach((i) => {
+                     svg += ` ${i}`
+                   })
+                   svg += `" stroke="${coltab[colNdx+1]}" stroke-width="${widtab[widNdx]}"/>`
+                 }
+               })
+               svg += '</g></svg>';
+               // console.log('svg:', svg)
+               src = `data:image/svg+xml;base64,${btoa(svg)}`;
+            } catch (error) {
+               console.error(error);
+               src = "data:null";
+            }
+            box += `<img src="${src}"`;
             box += 'alt="Drawing" width="100%">';
             txt = "";
         }