diff --git a/effects/kscreen/kscreen.cpp b/effects/kscreen/kscreen.cpp
--- a/effects/kscreen/kscreen.cpp
+++ b/effects/kscreen/kscreen.cpp
@@ -105,19 +105,36 @@
 
 void KscreenEffect::paintWindow(EffectWindow *w, int mask, QRegion region, WindowPaintData &data)
 {
-    switch (m_state) {
-    case StateFadingOut:
-        data.multiplyOpacity(1.0 - m_timeLine.currentValue());
-        break;
-    case StateFadedOut:
-        data.multiplyOpacity(0.0);
-        break;
-    case StateFadingIn:
-        data.multiplyOpacity(m_timeLine.currentValue());
-        break;
-    default:
-        // no adjustment
-        break;
+    if (w->hasAlpha()) {
+        switch (m_state) {
+        case StateFadingOut:
+            data.multiplyOpacity(1.0 - m_timeLine.currentValue());
+            break;
+        case StateFadedOut:
+            data.multiplyOpacity(0.0);
+            break;
+        case StateFadingIn:
+            data.multiplyOpacity(m_timeLine.currentValue());
+            break;
+        default:
+            // no adjustment
+            break;
+        }
+    } else {
+        switch (m_state) {
+        case StateFadingOut:
+            data.multiplyBrightness(1.0 - m_timeLine.currentValue());
+            break;
+        case StateFadedOut:
+            data.multiplyBrightness(0.0);
+            break;
+        case StateFadingIn:
+            data.multiplyBrightness(m_timeLine.currentValue());
+            break;
+        default:
+            // no adjustment
+            break;
+        }
     }
     effects->paintWindow(w, mask, region, data);
 }