diff --git a/blockly_uncompressed.js b/blockly_uncompressed.js
index 8c7996a6e..ccd5115ac 100644
--- a/blockly_uncompressed.js
+++ b/blockly_uncompressed.js
@@ -37,7 +37,7 @@ this.BLOCKLY_BOOT = function(root) {
 goog.addDependency("../../../" + dir + "/core/block.js", ['Blockly.Block'], ['Blockly.Blocks', 'Blockly.Comment', 'Blockly.Connection', 'Blockly.Events.BlockChange', 'Blockly.Events.BlockCreate', 'Blockly.Events.BlockDelete', 'Blockly.Events.BlockMove', 'Blockly.Extensions', 'Blockly.Input', 'Blockly.Mutator', 'Blockly.utils', 'Blockly.Warning', 'Blockly.Workspace', 'goog.math.Coordinate']);
 goog.addDependency("../../../" + dir + "/core/block_animations.js", ['Blockly.BlockAnimations'], ['Blockly.utils']);
 goog.addDependency("../../../" + dir + "/core/block_drag_surface.js", ['Blockly.BlockDragSurfaceSvg'], ['Blockly.utils', 'goog.math.Coordinate']);
-goog.addDependency("../../../" + dir + "/core/block_dragger.js", ['Blockly.BlockDragger'], ['Blockly.BlockAnimations', 'Blockly.DraggedConnectionManager', 'Blockly.Events.BlockMove', 'goog.math.Coordinate']);
+goog.addDependency("../../../" + dir + "/core/block_dragger.js", ['Blockly.BlockDragger'], ['Blockly.BlockAnimations', 'Blockly.InsertionMarkerManager', 'Blockly.Events.BlockMove', 'goog.math.Coordinate']);
 goog.addDependency("../../../" + dir + "/core/block_events.js", ['Blockly.Events.BlockBase', 'Blockly.Events.BlockChange', 'Blockly.Events.BlockCreate', 'Blockly.Events.BlockDelete', 'Blockly.Events.BlockMove', 'Blockly.Events.Change', 'Blockly.Events.Create', 'Blockly.Events.Delete', 'Blockly.Events.Move'], ['Blockly.Events', 'Blockly.Events.Abstract', 'Blockly.Xml.utils', 'goog.math.Coordinate']);
 goog.addDependency("../../../" + dir + "/core/block_render_svg.js", ['Blockly.BlockSvg.render'], ['Blockly.BlockSvg']);
 goog.addDependency("../../../" + dir + "/core/block_svg.js", ['Blockly.BlockSvg'], ['Blockly.Block', 'Blockly.BlockAnimations', 'Blockly.ContextMenu', 'Blockly.Events.Ui', 'Blockly.Events.BlockMove', 'Blockly.Grid', 'Blockly.RenderedConnection', 'Blockly.Tooltip', 'Blockly.Touch', 'Blockly.utils', 'goog.color', 'goog.math.Coordinate']);
@@ -77,6 +77,7 @@ goog.addDependency("../../../" + dir + "/core/grid.js", ['Blockly.Grid'], ['Bloc
 goog.addDependency("../../../" + dir + "/core/icon.js", ['Blockly.Icon'], ['Blockly.utils', 'goog.math.Coordinate']);
 goog.addDependency("../../../" + dir + "/core/inject.js", ['Blockly.inject'], ['Blockly.BlockDragSurfaceSvg', 'Blockly.Css', 'Blockly.Grid', 'Blockly.Options', 'Blockly.utils', 'Blockly.WorkspaceSvg', 'Blockly.WorkspaceDragSurfaceSvg', 'goog.ui.Component', 'goog.userAgent']);
 goog.addDependency("../../../" + dir + "/core/input.js", ['Blockly.Input'], ['Blockly.Connection', 'Blockly.FieldLabel']);
+goog.addDependency("../../../" + dir + "/core/insertion_marker_manager.js", ['Blockly.InsertionMarkerManager'], ['Blockly.BlockAnimations', 'Blockly.Events.BlockMove', 'Blockly.RenderedConnection', 'goog.math.Coordinate']);
 goog.addDependency("../../../" + dir + "/core/msg.js", ['Blockly.Msg'], []);
 goog.addDependency("../../../" + dir + "/core/mutator.js", ['Blockly.Mutator'], ['Blockly.Bubble', 'Blockly.Events.BlockChange', 'Blockly.Events.Ui', 'Blockly.Icon', 'Blockly.utils', 'Blockly.WorkspaceSvg', 'Blockly.Xml', 'Blockly.Xml.utils']);
 goog.addDependency("../../../" + dir + "/core/names.js", ['Blockly.Names'], []);
@@ -1786,6 +1787,7 @@ goog.require('Blockly.Grid');
 goog.require('Blockly.HorizontalFlyout');
 goog.require('Blockly.Icon');
 goog.require('Blockly.Input');
+goog.require('Blockly.InsertionMarkerManager');
 goog.require('Blockly.Msg');
 goog.require('Blockly.Mutator');
 goog.require('Blockly.Names');
diff --git a/core/connection.js b/core/connection.js
index 197b4c468..bff427814 100644
--- a/core/connection.js
+++ b/core/connection.js
@@ -357,48 +357,39 @@ Blockly.Connection.prototype.canConnectToPrevious_ = function(candidate) {
     return false;
   }
 
-  switch (candidate.type) {
-    case Blockly.PREVIOUS_STATEMENT:
-      // Don't offer to connect the bottom of a statement block to one that's
-      // already connected.
-      if (candidate.isConnected() || this.isConnected()) {
-        return false;
-      }
-      break;
-    case Blockly.OUTPUT_VALUE:
-      // Don't offer to connect an already connected left (male) value plug to
-      // an available right (female) value plug.
-      if (candidate.isConnected() || this.isConnected()) {
-        return false;
-      }
-      break;
-    case Blockly.INPUT_VALUE:
-      // Offering to connect the left (male) of a value block to an already
-      // connected value pair is ok, we'll splice it in.
-      // However, don't offer to splice into an unmovable block.
-      if (candidate.targetConnection &&
-          !candidate.targetBlock().isMovable() &&
-          !candidate.targetBlock().isShadow()) {
-        return false;
-      }
-      break;
-    case Blockly.NEXT_STATEMENT:
-      // Don't let a block with no next connection bump other blocks out of the
-      // stack.  But covering up a shadow block or stack of shadow blocks is
-      // fine.  Similarly, replacing a terminal statement with another terminal
-      // statement is allowed.
-      if (candidate.isConnected() &&
-          !this.sourceBlock_.nextConnection &&
-          !candidate.targetBlock().isShadow() &&
-          candidate.targetBlock().nextConnection) {
-        return false;
-      }
-      break;
-    default:
-      throw Error('Unknown connection type in isConnectionAllowed');
+  // Don't let blocks try to connect to themselves or ones they nest.
+  if (Blockly.draggingConnections_.indexOf(candidate) != -1) {
+    return false;
   }
 
-  return true;
+  var firstStatementConnection =
+      this.sourceBlock_.getFirstStatementConnection();
+  var isFirstStatementConnection = this == firstStatementConnection;
+  var isNextConnection = this == this.sourceBlock_.nextConnection;
+
+  // Complex blocks with no previous connection will not be allowed to connect
+  // mid-stack.
+  var sourceHasPreviousConn = this.sourceBlock_.previousConnection != null;
+
+  if (isNextConnection ||
+      (isFirstStatementConnection && !sourceHasPreviousConn)) {
+    // If the candidate is the first connection in a stack, we can connect.
+    if (!candidate.targetConnection) {
+      return true;
+    }
+
+    var targetBlock = candidate.targetBlock();
+    // If it is connected a real block, game over.
+    if (!targetBlock.isInsertionMarker()) {
+      return false;
+    }
+    // If it's connected to an insertion marker but that insertion marker
+    // is the first block in a stack, it's still fine.  If that insertion
+    // marker is in the middle of a stack, it won't work.
+    return !targetBlock.getPreviousBlock();
+  }
+  // ???
+  return false;
 };
 
 /**
diff --git a/core/insertion_marker_manager.js b/core/insertion_marker_manager.js
index b53f2adf4..10dbb6d0f 100644
--- a/core/insertion_marker_manager.js
+++ b/core/insertion_marker_manager.js
@@ -703,9 +703,7 @@ Blockly.InsertionMarkerManager.prototype.connectMarker_ = function() {
   imBlock.positionNewBlock(imBlock, imConn, closest);
 
   // Connect() also renders the insertion marker.
-  console.log("connecting the insertion marker");
   imConn.connect(closest);
-  console.log("done connecting the insertion marker");
   this.markerConnection_ = imConn;
 };
 
diff --git a/tests/jsunit/connection_db_test.js b/tests/jsunit/connection_db_test.js
index 1ef07c6b8..f488d5a96 100644
--- a/tests/jsunit/connection_db_test.js
+++ b/tests/jsunit/connection_db_test.js
@@ -279,6 +279,7 @@ function helper_searchDB(db, x, y, radius, shared_workspace) {
   var tempConn = helper_createConnection(x, y,
       Blockly.NEXT_STATEMENT, shared_workspace, true);
   tempConn.sourceBlock_ = helper_makeSourceBlock(shared_workspace);
+  tempConn.sourceBlock_.nextConnection = tempConn;
   var closest = db.searchForClosest(tempConn, radius, {x: 0, y: 0});
   return closest.connection;
 }