Hm somehow my log didn't make it in the last patch.

Change-Id: If7b3b041e478e1f05998323c02deb665f65073cb
diff --git a/services/java/com/android/server/WindowManagerService.java b/services/java/com/android/server/WindowManagerService.java
index 3cf8138..26dd692 100644
--- a/services/java/com/android/server/WindowManagerService.java
+++ b/services/java/com/android/server/WindowManagerService.java
@@ -4991,6 +4991,8 @@
         }
 
         if (rawss == null) {
+            Log.w(TAG, "Failure taking screenshot for (" + dw + "x" + dh
+                    + ") to layer " + maxLayer);
             return null;
         }