public void execute() {
      if (!isEditable() || !isEnabled()) {
        return;
      }

      try {
        int position = lastClickPoint != null ? viewToModel(lastClickPoint) : getCaretPosition();
        lastClickPoint = null;
        Document document = getDocument();
        String selectedText = getSelectedText();
        if (selectedText != null && !CommonUtil.isEmpty(selectedText)) {
          final int selectionEnd = getSelectionEnd();
          document.insertString(selectionEnd, selectedText, null);
          select(selectionEnd, selectionEnd + selectedText.length());
        } else {
          final int docLen = document.getLength();
          int fromIndex = Math.max(0, getText(0, position).lastIndexOf('\n'));
          int toIndex = getText(fromIndex + 1, docLen - fromIndex).indexOf('\n');
          toIndex = toIndex < 0 ? docLen : fromIndex + toIndex;
          String textToDuplicate = getText(fromIndex, toIndex - fromIndex + 1);
          if (!textToDuplicate.startsWith("\n")) {
            textToDuplicate = "\n" + textToDuplicate;
          }
          if (textToDuplicate.endsWith("\n")) {
            textToDuplicate = textToDuplicate.substring(0, textToDuplicate.length() - 1);
          }
          document.insertString(Math.min(docLen, toIndex + 1), textToDuplicate, null);
          setCaretPosition(position + textToDuplicate.length());
        }
      } catch (BadLocationException e1) {
        e1.printStackTrace();
      }
    }
    public void execute() {
      if (!isEditable() || !isEnabled()) {
        return;
      }
      int position = lastClickPoint != null ? viewToModel(lastClickPoint) : getCaretPosition();
      lastClickPoint = null;
      Document document = getDocument();
      String selectedText = getSelectedText();

      try {
        if (selectedText != null && !CommonUtil.isEmpty(selectedText)) {
          String trimmed = selectedText.trim();
          if (trimmed.startsWith("<!--") && trimmed.endsWith("-->")) {
            StringBuffer buffer = new StringBuffer(selectedText);
            int pos = buffer.indexOf("<!--");
            buffer.delete(pos, pos + 4);
            pos = buffer.lastIndexOf("-->");
            buffer.delete(pos, pos + 3);
            replaceSelection(buffer.toString());
          } else {
            String newSelection = "<!--" + selectedText + "-->";
            replaceSelection(newSelection);
          }
        } else {
          final int docLen = document.getLength();
          int fromIndex = Math.max(0, getText(0, position).lastIndexOf('\n'));
          int toIndex = getText(fromIndex + 1, docLen - position).indexOf('\n');
          toIndex = toIndex < 0 ? docLen : fromIndex + toIndex;
          String textToComment = getText(fromIndex, toIndex - fromIndex + 1);

          if (textToComment.startsWith("\n")) {
            textToComment = textToComment.substring(1);
            fromIndex++;
          }
          if (textToComment.endsWith("\n")) {
            textToComment = textToComment.substring(0, textToComment.length() - 1);
            toIndex--;
          }
          String trimmed = textToComment.trim();
          if (trimmed.startsWith("<!--") && trimmed.endsWith("-->")) {
            int pos = textToComment.lastIndexOf("-->");
            document.remove(fromIndex + pos, 3);
            pos = textToComment.indexOf("<!--");
            document.remove(fromIndex + pos, 4);
          } else {
            document.insertString(Math.min(toIndex + 1, docLen), "-->", null);
            document.insertString(fromIndex, "<!--", null);
          }
        }
      } catch (BadLocationException e1) {
        e1.printStackTrace();
      }
    }