WaitingDialog: Try fix deadlock.

src/View/WaitingDialog.py

@@ -90,6 +90,7 @@ class WaitingDialog(PamhyrDialog):
             options=[],
             parent=parent
         )
+        self._to_close = False
 
         self._payload_fn = payload_fn
 
@@ -131,7 +132,7 @@ class WaitingDialog(PamhyrDialog):
         )
 
     def end_worker(self):
-        self._worker_thread.terminate()
+        self._worker_thread.quit()
         self._worker_thread.wait()
 
     def close(self):
@@ -141,4 +142,12 @@ class WaitingDialog(PamhyrDialog):
         except Exception as e:
             logger_exception(e)
 
+        self._to_close = True
+
         super().close()
+
+    def closeEvent(self, event):
+        if self._to_close:
+            super().closeEvent(event)
+        else:
+            event.ignore()