OO-4239: new search parameters if search is cancelled

src/main/java/org/olat/modules/lecture/ui/AbstractTeacherOverviewController.java

@@ -299,7 +299,8 @@ public abstract class AbstractTeacherOverviewController extends BasicController
 			if(event instanceof SearchLecturesBlockEvent) {
 				doSearch((SearchLecturesBlockEvent)event);
 			} else if(event == Event.CANCELLED_EVENT) {
-				loadModel(null);
+				currentSearchParams = new LecturesBlockSearchParameters();
+				loadModel(currentSearchParams);
 			}
 		}
 		super.event(ureq, source, event);