Fix View.isCurrentView to account for wrapping

ViewSite wraps View objects inside of other panels before it
displays them, so we really need to consider unwrapping the
parent a couple of levels in order to find the parent ViewSite
and test for our instance.

Signed-off-by: Shawn O. Pearce <sop@google.com>
diff --git a/src/main/java/com/google/gwtexpui/user/client/View.java b/src/main/java/com/google/gwtexpui/user/client/View.java
index eed4333..87668a7 100644
--- a/src/main/java/com/google/gwtexpui/user/client/View.java
+++ b/src/main/java/com/google/gwtexpui/user/client/View.java
@@ -38,8 +38,14 @@
 
   /** true if this is the current view of its parent view site */
   public final boolean isCurrentView() {
-    final Widget p = getParent();
-    return p instanceof ViewSite && ((ViewSite<?>) p).getView() == this;
+    Widget p = getParent();
+    while (p != null) {
+      if (p instanceof ViewSite) {
+        return ((ViewSite<?>) p).getView() == this;
+      }
+      p = p.getParent();
+    }
+    return false;
   }
 
   /** Replace the current view in the parent ViewSite with this view. */