--- a/jdk/src/share/classes/javax/swing/text/AsyncBoxView.java	Mon Oct 14 13:22:36 2013 +0400
+++ b/jdk/src/share/classes/javax/swing/text/AsyncBoxView.java	Mon Oct 14 13:59:38 2013 +0400
@@ -827,8 +827,12 @@
      * location that one might place a caret.  Some views may not be visible,
      * they might not be in the same order found in the model, or they just
      * might not allow access to some of the locations in the model.
+     * This method enables specifying a position to convert
+     * within the range of >=0.  If the value is -1, a position
+     * will be calculated automatically.  If the value < -1,
+     * the {@code BadLocationException} will be thrown.
      *
-     * @param pos the position to convert >= 0
+     * @param pos the position to convert
      * @param a the allocated region to render into
      * @param direction the direction from the current position that can
      *  be thought of as the arrow keys typically found on a keyboard;
@@ -842,13 +846,17 @@
      * @param biasRet an array contain the bias that was checked
      * @return the location within the model that best represents the next
      *  location visual position
-     * @exception BadLocationException
+     * @exception BadLocationException the given position is not a valid
+     *                                 position within the document
      * @exception IllegalArgumentException if <code>direction</code> is invalid
      */
     public int getNextVisualPositionFrom(int pos, Position.Bias b, Shape a,
                                          int direction,
                                          Position.Bias[] biasRet)
                                                   throws BadLocationException {
+        if (pos < -1) {
+            throw new BadLocationException("invalid position", pos);
+        }
         return Utilities.getNextVisualPositionFrom(
                             this, pos, b, a, direction, biasRet);
     }