as there is no validator facility on checkbox, I created a validate method

I coded the following line: fld.markInvalid(); (fld is a checkbox)

but it doesn't trigger a red border on the checkbox.

and if I inspect fld.el.dom.getAttribute('class') in firebug it gives me "x-form-checkbox x-form-field". As you can see, there is no "x-form-invalid" class in it

I try to obtain a red border when I mark the check box invalid

Thank you in advance for your answers