Hide 'hide scrollbar and resize indicator' pref on Lion because it has no effect.

PreferencePanel.m

@@ -526,6 +526,7 @@ static float versionNumber;
     if (IsLionOrLater()) {
         [lionStyleFullscreen setHidden:NO];
+        [hideScrollbar setHidden:YES];
     } else {
         [lionStyleFullscreen setHidden:YES];
     }
@@ -1571,7 +1572,11 @@ static float versionNumber;
 - (BOOL)hideScrollbar
 {
-    return defaultHideScrollbar;
+    if (IsLionOrLater()) {
+        return NO;
+    } else {
+        return defaultHideScrollbar;
+    }
 }
 - (BOOL)smartPlacement