fix: use block glow to track project run status

This means that:
- Monitor blocks don't count, because they don't affect block glow (the
monitor block container has forceNoGlow set)
- Edge-activated hats with no stacks attached don't count (the block to
glow is null)
- Edge-activated hats whose predicates are false don't count (they're
evaluated outside stepThreads so block glow isn't set to true)

Basically, anything which would cause blocks to glow will cause the
project to be considered "running".

Author: adroitwhiz

src/engine/runtime.js

@@ -248,7 +248,7 @@ class Runtime extends EventEmitter {
         this._scriptGlowsPreviousFrame = [];
 
         /**
-         * Whether any non-monitor threads ran during the previous frame.
+         * Whether the project counted as "running" during the previous frame.
          * @type {boolean}
          */
         this._projectRanLastFrame = false;
@@ -1636,13 +1636,16 @@ class Runtime extends EventEmitter {
      * @param {?object} opts optional arguments
      * @param {?boolean} opts.stackClick true if the script was activated by clicking on the stack
      * @param {?boolean} opts.updateMonitor true if the script should update a monitor value
+     * @param {?boolean} opts.edgeActivated true if the script's top block is an edge-activated hat block
      * @return {!Thread} The newly created thread.
      */
     _pushThread (id, target, opts) {
         const thread = new Thread(id);
         thread.target = target;
+        // TODO: make these mutually exclusive (convert to an enum?)
         thread.stackClick = Boolean(opts && opts.stackClick);
         thread.updateMonitor = Boolean(opts && opts.updateMonitor);
+        thread.edgeActivated = Boolean(opts && opts.edgeActivated);
         thread.blockContainer = thread.updateMonitor ?
             this.monitorBlocks :
             target.blocks;
@@ -1817,6 +1820,7 @@ class Runtime extends EventEmitter {
         const newThreads = [];
         // Look up metadata for the relevant hat.
         const hatMeta = instance._hats[requestedHatOpcode];
+        const edgeActivated = Boolean(hatMeta.edgeActivated);
 
         for (const opts in optMatchFields) {
             if (!optMatchFields.hasOwnProperty(opts)) continue;
@@ -1869,7 +1873,7 @@ class Runtime extends EventEmitter {
                 }
             }
             // Start the thread with this top block.
-            newThreads.push(this._pushThread(topBlockId, target));
+            newThreads.push(this._pushThread(topBlockId, target, {edgeActivated}));
         }, optTarget);
         // For compatibility with Scratch 2, edge triggered hats need to be processed before
         // threads are stepped. See ScratchRuntime.as for original implementation
@@ -2094,11 +2098,15 @@ class Runtime extends EventEmitter {
         }
         this._updateGlows(doneThreads);
 
-        const threadNonMonitor = thread => !thread.updateMonitor;
+        // Threads count as "running" if a block glowed in the thread this frame.
+        // This excludes edge-activated hat predicates and monitor blocks.
+        const threadCountsTowardsRunStatus = thread => thread.requestScriptGlowInFrame &&
+            thread.blockGlowInFrame !== null;
         // Add done threads so that even if a thread finishes within 1 frame, the green
         // flag will still indicate that a script ran.
-        const anyNonMonitorThreadsRunning = this.threads.some(threadNonMonitor) || doneThreads.some(threadNonMonitor);
-        this._emitProjectRunStatus(anyNonMonitorThreadsRunning);
+        const anyThreadsRunning = this.threads.some(threadCountsTowardsRunStatus) ||
+            doneThreads.some(threadCountsTowardsRunStatus);
+        this._emitProjectRunStatus(anyThreadsRunning);
         // Store threads that completed this iteration for testing and other
         // internal purposes.
         this._lastStepDoneThreads = doneThreads;