Scenario: Add Discard option to scenario switching dialog.

src/View/Scenarios/GraphWidget.py

@@ -426,30 +426,35 @@ class GraphWidget(QGraphicsView):
 
         dlg.setWindowTitle(self._trad["mb_save_title"])
         dlg.setText(self._trad["mb_save_msg"])
-        opt = QMessageBox.Save | QMessageBox.Cancel
+        opt = QMessageBox.Cancel | QMessageBox.Save | QMessageBox.Discard
 
         dlg.setStandardButtons(opt)
         dlg.setIcon(QMessageBox.Warning)
         dlg.button(QMessageBox.Save).setText(self._trad["Save"])
+        dlg.button(QMessageBox.Discard).setText(self._trad["Don't save"])
         dlg.button(QMessageBox.Cancel).setText(self._trad["Cancel"])
 
         res = dlg.exec()
 
         if res == QMessageBox.Save:
-            return True
+            return "Save"
         elif res == QMessageBox.Cancel:
-            return False
+            return "Cancel"
+        else:
+            return "Discard"
 
     def select_scenario(self, item):
         if type(item) is not ScenarioItem:
             return
 
-        must_saved = self.dialog_save()
+        must_save = self.dialog_save()
+        if must_save == "Cancel":
+            return
 
         def fn():
             self._close_other_window()
 
-            if must_saved:
+            if must_save == "Save":
                 self._study.save()
 
             self._undo.push(

src/View/Translate.py

@@ -281,6 +281,7 @@ class MainTranslate(UnitTranslate):
         self._dict["No"] = _translate("MainWindow", "No")
         self._dict["Cancel"] = _translate("MainWindow", "Cancel")
         self._dict["Save"] = _translate("MainWindow", "Save")
+        self._dict["Don't save"] = _translate("MainWindow", "Don't save")
         self._dict["Close"] = _translate("MainWindow", "Close")
         self._dict["Solver"] = _translate("MainWindow", "Solver")