// Display overlay dialog with a view to prevent home button click
 public void lock(Activity activity) {
   if (mOverlayDialog == null) {
     mOverlayDialog = new OverlayDialog(activity);
     mOverlayDialog.show();
     mLockStatusChangedListener = (OnLockStatusChangedListener) activity;
   }
 }
 public void lock(Activity activity) {
   if (mOverlayDialog == null) {
     mOverlayDialog = new OverlayDialog(activity);
     mOverlayDialog.show();
   }
 }