diff --git a/include/ui/Region.h b/include/ui/Region.h
index ffcd429ae..ce91f3b69 100644
--- a/include/ui/Region.h
+++ b/include/ui/Region.h
@@ -108,6 +108,10 @@ public:
     inline  Region&     operator += (const Point& pt);
 
     
+    // returns true if the regions share the same underlying storage
+    bool isTriviallyEqual(const Region& region) const;
+
+
     /* various ways to access the rectangle list */
 
     
diff --git a/libs/ui/Region.cpp b/libs/ui/Region.cpp
index 488fba32c..bf01488ca 100644
--- a/libs/ui/Region.cpp
+++ b/libs/ui/Region.cpp
@@ -239,6 +239,10 @@ void Region::set(uint32_t w, uint32_t h)
     mStorage.add(Rect(w,h));
 }
 
+bool Region::isTriviallyEqual(const Region& region) const {
+    return begin() == region.begin();
+}
+
 // ----------------------------------------------------------------------------
 
 void Region::addRectUnchecked(int l, int t, int r, int b)
diff --git a/services/surfaceflinger/Layer.cpp b/services/surfaceflinger/Layer.cpp
index a4c613cb8..2302367bb 100644
--- a/services/surfaceflinger/Layer.cpp
+++ b/services/surfaceflinger/Layer.cpp
@@ -881,8 +881,7 @@ bool Layer::setMatrix(const layer_state_t::matrix22_t& matrix) {
     return true;
 }
 bool Layer::setTransparentRegionHint(const Region& transparent) {
-    mCurrentState.sequence++;
-    mCurrentState.transparentRegion = transparent;
+    mCurrentState.requestedTransparentRegion = transparent;
     setTransactionFlags(eTransactionNeeded);
     return true;
 }
@@ -1008,7 +1007,6 @@ Region Layer::latchBuffer(bool& recomputeVisibleRegions)
                     swap(bufWidth, bufHeight);
                 }
 
-
                 bool isFixedSize = item.mScalingMode != NATIVE_WINDOW_SCALING_MODE_FREEZE;
                 if (front.active != front.requested) {
 
@@ -1061,6 +1059,17 @@ Region Layer::latchBuffer(bool& recomputeVisibleRegions)
                         return true;
                     }
                 }
+
+                // if the transparent region has changed (this test is
+                // conservative, but that's fine, worst case we're doing
+                // a bit of extra work), we latch the new one and we
+                // trigger a visible-region recompute.
+                if (!front.activeTransparentRegion.isTriviallyEqual(
+                        front.requestedTransparentRegion)) {
+                    front.activeTransparentRegion = front.requestedTransparentRegion;
+                    recomputeVisibleRegions = true;
+                }
+
                 return false;
             }
         };
@@ -1168,7 +1177,7 @@ void Layer::dump(String8& result, char* buffer, size_t SIZE) const
             getTypeId(), this, getName().string());
     result.append(buffer);
 
-    s.transparentRegion.dump(result, "transparentRegion");
+    s.activeTransparentRegion.dump(result, "transparentRegion");
     visibleRegion.dump(result, "visibleRegion");
     sp<Client> client(mClientRef.promote());
 
diff --git a/services/surfaceflinger/Layer.h b/services/surfaceflinger/Layer.h
index 6bca9413a..2765db1be 100644
--- a/services/surfaceflinger/Layer.h
+++ b/services/surfaceflinger/Layer.h
@@ -103,7 +103,11 @@ public:
         uint8_t reserved[2];
         int32_t sequence; // changes when visible regions can change
         Transform transform;
-        Region transparentRegion;
+        // the transparentRegion hint is a bit special, it's latched only
+        // when we receive a buffer -- this is because it's "content"
+        // dependent.
+        Region activeTransparentRegion;
+        Region requestedTransparentRegion;
     };
 
     class LayerMesh {
diff --git a/services/surfaceflinger/SurfaceFlinger.cpp b/services/surfaceflinger/SurfaceFlinger.cpp
index 3ed8b1b2e..5c7cf0758 100644
--- a/services/surfaceflinger/SurfaceFlinger.cpp
+++ b/services/surfaceflinger/SurfaceFlinger.cpp
@@ -1360,14 +1360,14 @@ void SurfaceFlinger::computeVisibleRegions(
                     if (tr.transformed()) {
                         if (tr.preserveRects()) {
                             // transform the transparent region
-                            transparentRegion = tr.transform(s.transparentRegion);
+                            transparentRegion = tr.transform(s.activeTransparentRegion);
                         } else {
                             // transformation too complex, can't do the
                             // transparent region optimization.
                             transparentRegion.clear();
                         }
                     } else {
-                        transparentRegion = s.transparentRegion;
+                        transparentRegion = s.activeTransparentRegion;
                     }
                 }