prevent crash where effects doesn't get set up properly; e.g. opengl is selected or is the default but it can't initialize / find support as needed in the opengl implementation

svn path=/trunk/KDE/kdebase/workspace/; revision=671104

workspace.cpp

@@ -1046,7 +1046,10 @@ void Workspace::slotReconfigure()
     if( options->useTranslucency )
     {
         setupCompositing();
-        effects->reconfigure();
+        if( effects )
+        {
+            effects->reconfigure();
+        }
     }
     else
         finishCompositing();