Obligatory checkbox

Yes, but it's a bit awkward. Since the checkbox is a binary value, it's not typically considered something you'd make requred, and the "Required" option is not provided. You have to edit the XML to put the option in.

First though, in the "Options->Binding" tab for the checkbox, delete the "Off" value, so that "off" for the check box is a null value.Next, add a text field to the document and make it required. With the text field selected switch to the XML view. Scroll down to the bottom of the text feild tab and you'll see an entry for the "validate" event. It'll have a "nulltest" property. Copy this line to the same location in the checkbox's field tag. Switch back to design view and accept the changes. Now delete the text field you created.

That's it. When the user tries to do the submit they'll get the checkbox flagged and highlighted as required, just like the other required fields.