Don't connect to blocks under the flyout.

core/block_svg.js

@@ -690,7 +690,12 @@ Blockly.BlockSvg.prototype.onMouseUp_ = function(e) {
         new Blockly.Events.Ui(this, 'click', undefined, undefined));
   }
   Blockly.terminateDrag_();
-  if (Blockly.selected && Blockly.highlightedConnection_) {
+
+  var deleteArea = this.workspace.isDeleteArea(e);
+
+  // Connect to a nearby block, but not if it's over the toolbox.
+  if (Blockly.selected && Blockly.highlightedConnection_ &&
+      deleteArea != Blockly.DELETE_AREA_TOOLBOX) {
     // Connect two blocks together.
     Blockly.localConnection_.connect(Blockly.highlightedConnection_);
     if (this.rendered) {
@@ -704,8 +709,9 @@ Blockly.BlockSvg.prototype.onMouseUp_ = function(e) {
       // Don't throw an object in the trash can if it just got connected.
       this.workspace.trashcan.close();
     }
-  } else if (!this.getParent() && Blockly.selected.isDeletable() &&
-      this.workspace.isDeleteArea(e)) {
+  } else if (deleteArea && !this.getParent() && Blockly.selected.isDeletable()) {
+    // We didn't connect the block, and it was over the trash can or the
+    // toolbox.  Delete it.
     var trashcan = this.workspace.trashcan;
     Blockly.confirmDeletion(function(confirmedDelete) {
       if (trashcan) {
@@ -1024,24 +1030,57 @@ Blockly.BlockSvg.prototype.onMouseMove_ = function(e) {
       Blockly.highlightedConnection_ = null;
       Blockly.localConnection_ = null;
     }
+
+    var wouldDeleteBlock = this.updateCursor_(e, closestConnection);
+
     // Add connection highlighting if needed.
-    if (closestConnection &&
+    if (!wouldDeleteBlock && closestConnection &&
         closestConnection != Blockly.highlightedConnection_) {
       closestConnection.highlight();
       Blockly.highlightedConnection_ = closestConnection;
       Blockly.localConnection_ = localConnection;
     }
-    // Provide visual indication of whether the block will be deleted if
-    // dropped here.
-    if (this.isDeletable()) {
-      this.workspace.isDeleteArea(e);
-    }
   }
   // This event has been handled.  No need to bubble up to the document.
   e.stopPropagation();
   e.preventDefault();
 };
 
+/**
+ * Provide visual indication of whether the block will be deleted if
+ * dropped here.
+ * Prefer connecting over dropping into the trash can, but prefer dragging to
+ * the toolbox over connecting to other blocks.
+ * @param {!Event} e Mouse move event.
+ * @param {Blockly.Connection} closestConnection The connection this block would
+ *     potentially connect to if dropped here, or null.
+ * @return {boolean} True if the block would be deleted if dropped here,
+ *     otherwise false.
+ * @private
+ */
+Blockly.BlockSvg.prototype.updateCursor_ = function(e, closestConnection) {
+  var deleteArea = this.workspace.isDeleteArea(e);
+  var wouldConnect = Blockly.selected && closestConnection &&
+      deleteArea != Blockly.DELETE_AREA_TOOLBOX;
+  var wouldDelete = deleteArea && !this.getParent() &&
+      Blockly.selected.isDeletable();
+  var showDeleteCursor = wouldDelete && !wouldConnect;
+
+  if (showDeleteCursor) {
+    Blockly.Css.setCursor(Blockly.Css.Cursor.DELETE);
+    if (deleteArea == Blockly.DELETE_AREA_TRASH && this.workspace.trashcan) {
+      this.workspace.trashcan.setOpen_(true);
+    }
+    return true;
+  } else {
+    Blockly.Css.setCursor(Blockly.Css.Cursor.CLOSED);
+    if (this.workspace.trashcan) {
+      this.workspace.trashcan.setOpen_(false);
+    }
+    return false;
+  }
+};
+
 /**
  * Add or remove the UI indicating if this block is movable or not.
  */

core/constants.js

@@ -200,3 +200,17 @@ Blockly.TOOLBOX_AT_LEFT = 2;
  * @const
  */
 Blockly.TOOLBOX_AT_RIGHT = 3;
+
+
+/**
+ * ENUM representing that an event is in the delete area of the trash can.
+ * @const
+ */
+Blockly.DELETE_AREA_TRASH = 1;
+
+/**
+ * ENUM representing that an event is in the delete area of the toolbox or
+ * flyout.
+ * @const
+ */
+Blockly.DELETE_AREA_TOOLBOX = 2;

core/workspace_svg.js

@@ -875,26 +875,18 @@ Blockly.WorkspaceSvg.prototype.recordDeleteAreas = function() {
  * Is the mouse event over a delete area (toolbox or non-closing flyout)?
  * Opens or closes the trashcan and sets the cursor as a side effect.
  * @param {!Event} e Mouse move event.
- * @return {boolean} True if event is in a delete area.
+ * @return {?number} Null if not over a delete area, or an enum representing
+ *     which delete area the event is over.
  */
 Blockly.WorkspaceSvg.prototype.isDeleteArea = function(e) {
   var xy = new goog.math.Coordinate(e.clientX, e.clientY);
-  if (this.deleteAreaTrash_) {
-    if (this.deleteAreaTrash_.contains(xy)) {
-      this.trashcan.setOpen_(true);
-      Blockly.Css.setCursor(Blockly.Css.Cursor.DELETE);
-      return true;
-    }
-    this.trashcan.setOpen_(false);
+  if (this.deleteAreaTrash_ && this.deleteAreaTrash_.contains(xy)) {
+    return Blockly.DELETE_AREA_TRASH;
   }
-  if (this.deleteAreaToolbox_) {
-    if (this.deleteAreaToolbox_.contains(xy)) {
-      Blockly.Css.setCursor(Blockly.Css.Cursor.DELETE);
-      return true;
-    }
+  if (this.deleteAreaToolbox_ && this.deleteAreaToolbox_.contains(xy)) {
+    return Blockly.DELETE_AREA_TOOLBOX;
   }
-  Blockly.Css.setCursor(Blockly.Css.Cursor.CLOSED);
-  return false;
+  return null;
 };
 
 /**