move graphic operation to the same thread
diff --git a/sync-demo.pro b/sync-demo.pro
index 2eae1a3..24fcdd1 100644
--- a/sync-demo.pro
+++ b/sync-demo.pro
@@ -1,5 +1,6 @@
 TEMPLATE = app
 TARGET = sync-demo
+DEFINES += __DEBUG
 HEADERS = chatdialog.h \
           digesttreescene.h \
           settingdialog.h \