new "send (msg) to (sprite)" primitive

src/objects.js

@@ -84,7 +84,7 @@ BlockEditorMorph, BlockDialogMorph, PrototypeHatBlockMorph,  BooleanSlotMorph,
 localize, TableMorph, TableFrameMorph, normalizeCanvas, VectorPaintEditorMorph,
 HandleMorph, AlignmentMorph, Process, XML_Element, WorldMap, copyCanvas*/
 
-modules.objects = '2020-April-25';
+modules.objects = '2020-April-26';
 
 var SpriteMorph;
 var StageMorph;
@@ -741,6 +741,11 @@ SpriteMorph.prototype.initBlocks = function () {
             category: 'control',
             spec: 'message'
         },
+        doSend: {
+            type: 'command',
+            category: 'control',
+            spec: 'send %msg to %spr'
+        },
         doWait: {
             type: 'command',
             category: 'control',
@@ -2363,6 +2368,7 @@ SpriteMorph.prototype.blockTemplates = function (category) {
         blocks.push('-');
         blocks.push(block('doBroadcast'));
         blocks.push(block('doBroadcastAndWait'));
+        blocks.push(block('doSend'));
         blocks.push(watcherToggle('getLastMessage'));
         blocks.push(block('getLastMessage'));
         blocks.push('-');
@@ -8439,6 +8445,7 @@ StageMorph.prototype.blockTemplates = function (category) {
         blocks.push('-');
         blocks.push(block('doBroadcast'));
         blocks.push(block('doBroadcastAndWait'));
+        blocks.push(block('doSend'));
         blocks.push(watcherToggle('getLastMessage'));
         blocks.push(block('getLastMessage'));
         blocks.push('-');

src/threads.js

@@ -61,7 +61,7 @@ StageMorph, SpriteMorph, StagePrompterMorph, Note, modules, isString, copy, Map,
 isNil, WatcherMorph, List, ListWatcherMorph, alert, console, TableMorph, Color,
 TableFrameMorph, ColorSlotMorph, isSnapObject, newCanvas, Symbol, SVG_Costume*/
 
-modules.threads = '2020-April-25';
+modules.threads = '2020-April-26';
 
 var ThreadManager;
 var Process;
@@ -3287,6 +3287,20 @@ Process.prototype.getLastMessage = function () {
     return '';
 };
 
+Process.prototype.doSend = function (message, target) {
+    var stage = this.homeContext.receiver.parentThatIsA(StageMorph);
+    this.doBroadcast(
+        new List(
+            [
+                message,
+                target instanceof List ? target :
+                    target === stage.name ? new List([stage]) :
+                        new List([target])
+            ]
+        )
+    );
+};
+
 // Process type inference
 
 Process.prototype.reportIsA = function (thing, typeString) {