Add comment about an earlier All Apps bug fix

(earlier change was Icfdb096c: Fix bug where only holo outlines were visible in All Apps sometimes)
diff --git a/src/com/android/launcher2/PagedView.java b/src/com/android/launcher2/PagedView.java
index cb95235..159e821 100644
--- a/src/com/android/launcher2/PagedView.java
+++ b/src/com/android/launcher2/PagedView.java
@@ -546,6 +546,11 @@
                         alpha = 1.0f;
                     }
 
+                    // Due to the way we're setting alpha on our children in PagedViewCellLayout,
+                    // this optimization causes alpha to not be properly updated sometimes (repro
+                    // case: in xlarge mode, swipe to second page in All Apps, then click on "My
+                    // Apps" tab. the page will have alpha 0 until you swipe it). Removing
+                    // optimization fixes the issue, but we should fix this in a better manner
                     //if (Float.compare(alpha, layout.getAlpha()) != 0) {
                         layout.setAlpha(alpha);
                     //}