Do not start dim previous window animation for windows that should not be dimmed.

BUG: 194336

svn path=/trunk/KDE/kdebase/workspace/; revision=973936

effects/diminactive/diminactive.cpp

@@ -109,6 +109,8 @@ void DimInactiveEffect::windowActivated( EffectWindow* w )
         {
         previousActive = active;
         previousActiveTimeline.setProgress( 0.0 );
+        if( !dimWindow( previousActive ) )
+            previousActive = NULL;
 
         if( dim_by_group )
             {