add to watchwindow was missing an update.

src/plugins/debugger/watchhandler.cpp

@@ -877,9 +877,9 @@ void WatchHandler::watchExpression(const QString &exp)
     data.name = exp;
     data.iname = "watch." + exp;
     insertData(data);
+    emit watchModelUpdateRequested();
 }
 
-
 void WatchHandler::setDisplayedIName(const QString &iname, bool on)
 {
     WatchData *d = findData(iname);