MessageManager: Fix constant broken by 527046ac

Task-number: QTCREATORBUG-10255
Change-Id: I3d8ffd8441c5bb5f3dc39b1cdbb4e82740e5d4ea
Reviewed-by: David Schulz <david.schulz@digia.com>

src/plugins/coreplugin/messagemanager.h

@@ -55,7 +55,7 @@ public:
         WithFocus      = IOutputPane::WithFocus,
         EnsureSizeHint = IOutputPane::EnsureSizeHint,
         Silent         = 256,
-        Flash          = 51
+        Flash          = 512
     };
 
     Q_DECLARE_FLAGS(PrintToOutputPaneFlags, PrintToOutputPaneFlag)