Visibility of processing message is now correct when switching between views.

CURA-971

plugins/CuraEngineBackend/ProcessSlicedObjectListJob.py

@@ -151,6 +151,7 @@ class ProcessSlicedObjectListJob(Job):
             if Application.getInstance().getController().getActiveView().getPluginId() == "LayerView":
                 if not self._progress:
                     self._progress = Message(catalog.i18nc("@info:status", "Processing Layers"), 0, False, 0)
+                if self._progress.getProgress() != 100:
                     self._progress.show()
             else:
                 if self._progress: