Provides a form submit button (<input type=submit>).
This is most useful when the form contains multiple submit buttons and the
application needs to know which was actually pressed.
Parameters
- disabled
If true, the submit button will be
disabled.
The disabled attribute is ignored by Netscape Navigator 4).
- label
The label to put on the button.
- selected
A property updated if the button is the one clicked
to submit the form.
- tag
The value applied to the selected property if the button
is the one clicked to submit the form.