android中的工具栏和DialogFragment

Question

有什么方法可以在活动工具栏下添加transculent对话框？ 这是我的布局：

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
              android:layout_width="match_parent"
              android:layout_height="match_parent"
              android:orientation="vertical">

    <android.support.v7.widget.Toolbar
            android:id="@+id/toolbar"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:background="?colorPrimary"
            android:minHeight="?attr/actionBarSize"/>


    <WebView
            android:id="@+id/sa"
            android:layout_width="match_parent"
            android:layout_height="match_parent"/>

</LinearLayout>

和对话框的代码：

public class TransparentProgressDialog extends DialogFragment {

   private boolean mDialogCancelable = false;

   private boolean mBackButtonPressed = false;

   private OnDismissAfterBackPressed mOnDismissAfterBackPressed = null;

   public static TransparentProgressDialog getInstance() {
      TransparentProgressDialog transparentProgressDialog = new TransparentProgressDialog();
      return transparentProgressDialog;
   }

   public static void dismiss(TransparentProgressDialog dialog) {
      if (dialog != null) {
         try {
            dialog.dismissAllowingStateLoss();
         } catch (Exception e) {
            try {
               dialog.dismiss();
            } catch (Exception ex) {
               Timber.e(ex, "TransparentProgressDialog dismiss");
            }
         }
      }
   }

   @Override
   public void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      this.setCancelable(mDialogCancelable);
   }

   @Override
   public Dialog onCreateDialog(Bundle savedInstanceState) {
      Dialog dialog = new Dialog(getActivity(), android.R.style.Theme_Translucent_NoTitleBar);
      dialog.setContentView(R.layout.transparent_progress_bar);

      dialog.setOnKeyListener(new DialogInterface.OnKeyListener() {
         @Override
         public boolean onKey(DialogInterface dialogInterface, int i, KeyEvent keyEvent) {
            if (keyEvent.getKeyCode() == KeyEvent.KEYCODE_BACK) {
               Timber.d("back button pressed");
               mBackButtonPressed = true;
            }

            return false;
         }
      });

      return dialog;
   }

   @Override
   public void onStart() {
      super.onStart();
      Window window = getDialog().getWindow();
      WindowManager.LayoutParams params = window.getAttributes();
      params.dimAmount = 0.7f;
      params.flags |= WindowManager.LayoutParams.FLAG_DIM_BEHIND;
      window.setAttributes(params);
   }

   @Override
   public void onDismiss(DialogInterface dialog) {
      super.onDismiss(dialog);

      if (mDialogCancelable && mBackButtonPressed && mOnDismissAfterBackPressed != null) {
         mOnDismissAfterBackPressed.backPressed();
      }
   }

   public TransparentProgressDialog setCancelableDialog(boolean cancelable) {
      this.mDialogCancelable = cancelable;
      return this;
   }

   public TransparentProgressDialog setOnDismissAfterBackPressed(OnDismissAfterBackPressed onDismissAfterBackPressed) {
      this.mOnDismissAfterBackPressed = onDismissAfterBackPressed;
      return this;
   }

   public interface OnDismissAfterBackPressed {

      void backPressed();
   }
}

此对话框始终位于我的工具栏上。我怎么能避免这种情况？