Codename One: How do I define the pressed image for a checkbox

In our project, we customized the checkbox(Un)CheckedImage, as shown in below screenshot h t t p://i.stack.imgur.com/og5YC.png This works fine, but if we press the checkbox, it shrinks and changes color, as shown in the right side of below screenshot http://ift.tt/1Jy5Wua I cannot find a constant names “checkBoxPressed…”, as indicated below http://ift.tt/1njBKZn