Ensemble: Create new ensemble scenario.

src/View/Scenarios/GraphWidget.py

@@ -526,6 +526,26 @@ class GraphWidget(QGraphicsView):
         self.exec_with_waiting_window(fn, "duplicate_scenario")
         self.changeScenario.emit(self.sender())
 
+    def create_ensemble_scenario(self, item):
+        must_save = self.dialog_save()
+        if must_save == "Cancel":
+            return
+
+        def fn():
+            self._close_other_window()
+
+            if must_save == "Save":
+                self._study.save()
+
+            self._undo.push(
+                CreateEnsembleScenarioCommand(
+                    self._study,
+                )
+            )
+
+        self.exec_with_waiting_window(fn, "create_ensemble_scenario")
+        self.changeScenario.emit(self.sender())
+
     def _close_other_window(self):
         self.parent\
             .parent\