App: add method DocumentObject::getFirstParent()

src/App/DocumentObject.cpp

@@ -897,6 +897,17 @@ std::vector<std::pair<App::DocumentObject *,std::string>> DocumentObject::getPar
     return ret;
 }
 
+App::DocumentObject* DocumentObject::getFirstParent() const
+{
+    for (auto obj : getInList()) {
+        if (obj->hasExtension(App::GroupExtension::getExtensionClassTypeId(), true)) {
+            return obj;
+        }
+    }
+
+    return nullptr;
+}
+
 DocumentObject *DocumentObject::getLinkedObject(
         bool recursive, Base::Matrix4D *mat, bool transform, int depth) const 
 {

src/App/DocumentObject.h

@@ -383,6 +383,9 @@ public:
     ///Obtain top parents and subnames of this object using its InList
     std::vector<std::pair<App::DocumentObject*,std::string> > getParents(int depth=0) const;
 
+    /// Obtain the first parent group of this object
+    App::DocumentObject* getFirstParent() const;
+
     /** Return the linked object with optional transformation
      *
      * @param recurse: If false, return the immediate linked object, or else