Amaya 8.7.1/9.0 WinXP bug: Removing checked attribute in a checkbox

Hi,

The "Remove attribute" button in the Attributes window does not work 
when applied to a checked checkbox.

Steps to reproduce in Amaya 8.7.1 (the problem is present in Amaya 9.0 too):

1. Insert a checkbox control (XHTML > Form > Checkbox).
    The source code is then:
      <p><input type="checkbox" /></p>
2. Select the checkbox, open "Attributes > checked" menu and click
    "yes", "Apply", and "Close"  button.
    The source code is then:
      <p><input type="checkbox" checked="checked" /></p>
3. Select the checkbox, open "Attributes > checked" menu and click
    "Remove and "Close" button.
    The source code is still:
      <p><input type="checkbox" checked="checked" /></p>

Best regards,
Bartolomé Sintes (http://www.mclibre.org)