diff --git a/HISTORY.md b/HISTORY.md
index b3c9706e..9019e91b 100755
--- a/HISTORY.md
+++ b/HISTORY.md
@@ -2,10 +2,15 @@
 
 ## in development:
 
-* **New Features:**
+* **New Minor Features:**
     * added "bar / lines" option for plotting charts in the "frequency distribution analysis" library
     * new "add comment" option in the block context menu, thanks, Rob Fidler!
     * new "48 kHz" option in the "sampling rate" dropdown 
+* **Notable Changes:**
+    * specifying alpha values are now optional for generating pixels in bitmaps (costumes), none means the pixel is solid 
+
+### 2020-10-04
+* threads: made alpha values optional for generating costume pixels, none = solid
 
 ### 2020-09-28
 * tweaked "frequency distribution analysis" library to plot lines in any color or style
diff --git a/snap.html b/snap.html
index bcf9a429..981f7576 100755
--- a/snap.html
+++ b/snap.html
@@ -9,7 +9,7 @@
         <script src="src/symbols.js?version=2020-07-21"></script>
         <script src="src/widgets.js?version=2020-07-27"></script>
         <script src="src/blocks.js?version=2020-09-25"></script>
-        <script src="src/threads.js?version=2020-09-02"></script>
+        <script src="src/threads.js?version=2020-10-04"></script>
         <script src="src/objects.js?version=2020-09-18"></script>
         <script src="src/gui.js?version=2020-09-25"></script>
         <script src="src/paint.js?version=2020-05-17"></script>
diff --git a/src/threads.js b/src/threads.js
index 2efec49b..32d03ad2 100644
--- a/src/threads.js
+++ b/src/threads.js
@@ -61,7 +61,7 @@ StageMorph, SpriteMorph, StagePrompterMorph, Note, modules, isString, copy, Map,
 isNil, WatcherMorph, List, ListWatcherMorph, alert, console, TableMorph, BLACK,
 TableFrameMorph, ColorSlotMorph, isSnapObject, newCanvas, Symbol, SVG_Costume*/
 
-modules.threads = '2020-September-02';
+modules.threads = '2020-October-04';
 
 var ThreadManager;
 var Process;
@@ -5560,9 +5560,10 @@ Process.prototype.reportNewCostume = function (pixels, width, height, name) {
     dta = ctx.createImageData(width, height);
     for (i = 0; i < src.length; i += 1) {
         px = src[i].asArray();
-        for (k = 0; k < 4; k += 1) {
+        for (k = 0; k < 3; k += 1) {
             dta.data[(i * 4) + k] = px[k];
         }
+        dta.data[i * 4 + 3] = (px[3] === undefined ? 255 : px[3]);
     }
     ctx.putImageData(dta, 0, 0);
     return new Costume(