Clickjacking

Clickjacking, as defined on Wikipedia, is "a malicious technique of tricking a user into clicking on something different from what the user perceives, thus potentially revealing confidential information or allowing others to take control of their computer while clicking on seemingly innocuous objects, including web pages."

HTMLForm

If you are using HTMLForm and you want to allow framing of the form, you need to override HTMLForm's displayForm function and call $wgOut ->allowClickjacking(); on the overridden function.

See also