fix(rules): restrict movement on flow elements only

For the moment we allow moving flow elements in between diagrams, only.

lib/features/modeling/rules/ModelingRules.js

@@ -53,6 +53,26 @@ ModelingRules.prototype.init = function() {
     }
   });
 
+  /**
+   * Can an element be dropped into the target element
+   *
+   * @return {Boolean}
+   */
+  function canDrop(businessObject, targetBusinessObject, targetDi) {
+
+    if (businessObject.$instanceOf('bpmn:FlowElement') &&
+        targetBusinessObject.$instanceOf('bpmn:FlowElementsContainer')) {
+
+      // may not drop into collapsed sub processes
+      if (targetDi.isExpanded === false) {
+        return false;
+      }
+
+      return true;
+    }
+
+    return false;
+  }
 
   this.addRule('shapes.move', function(context) {
 
@@ -60,7 +80,7 @@ ModelingRules.prototype.init = function() {
         shapes = context.shapes;
 
     // only move if they have the same parent
-    var sameParent = _.size(_.groupBy(shapes, function(s) { return s.parent && s.parent.id; }));
+    var sameParent = _.size(_.groupBy(shapes, function(s) { return s.parent && s.parent.id; })) === 1;
 
     if (!sameParent) {
       return false;
@@ -73,18 +93,9 @@ ModelingRules.prototype.init = function() {
     var targetBusinessObject = target.businessObject,
         targetDi = targetBusinessObject.di;
 
-    // allow to drop elements elements into sub processes
-    // unless they are participants or lanes themselves
-
-    if (targetBusinessObject.$instanceOf('bpmn:SubProcess') && targetDi.isExpanded) {
-
-      return shapes.every(function(shape) {
-        var bo = shape.businessObject;
-        return !(bo.$instanceOf('bpmn:Participant') || bo.$instanceOf('bpmn:Lane'));
+    return shapes.every(function(s) {
+      return canDrop(s.businessObject, targetBusinessObject, targetDi);
     });
-    } else {
-      return false;
-    }
   });
 
 };