fixed mouseDown events for touch devices

HISTORY.md

@@ -2,6 +2,9 @@
 
 ## in development:
 
+### 2020-07-23
+* morphic: fixed mouseDown events for touch devices
+
 ### 2020-07-22
 * morphic, blocks, gui: tweaked block-fading mouse-over
 * blocks, threads: tweaked context visualizations to be alpha-independent

snap.html

@@ -4,7 +4,7 @@
         <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
         <title>Snap! Build Your Own Blocks 6.0.1 - dev -</title>
         <link rel="icon" href="src/favicon.ico">
-        <script src="src/morphic.js?version=2020-07-22"></script>
+        <script src="src/morphic.js?version=2020-07-23"></script>
         <script src="src/symbols.js?version=2020-07-21"></script>
         <script src="src/widgets.js?version=2020-07-21"></script>
         <script src="src/blocks.js?version=2020-07-22"></script>

src/morphic.js

@@ -1280,7 +1280,7 @@
 
 /*global window, HTMLCanvasElement, FileReader, Audio, FileList, Map*/
 
-var morphicVersion = '2020-July-22';
+var morphicVersion = '2020-July-23';
 var modules = {}; // keep track of additional loaded modules
 var useBlurredShadows = true;
 
@@ -11284,10 +11284,12 @@ HandMorph.prototype.processMouseDown = function (event) {
         posInDocument = getDocumentPositionOf(this.world.worldCanvas);
 
     // update my position, in case I've just been initialized
-    this.setPosition(new Point(
-        event.pageX - posInDocument.x,
-        event.pageY - posInDocument.y
-    ));
+    if (event.pageX) {
+        this.setPosition(new Point(
+            event.pageX - posInDocument.x,
+            event.pageY - posInDocument.y
+        ));
+    }
 
     // process the actual event
     this.destroyTemporaries();