title: TriCheckbox in form?
body: <p>I'm trying to make a form which allows TriCheckboxes.</p>
  
  <p>For example, it starts out blank, when you click it, it gets ticked, if you click it again it becomes a cross, and if you click it a final time, it becomes blank again.</p>
  
  <p>I've played around with javascript and classes and managed to get the graphics working, but how would I do so a TriCheckbox would work in a php form?</p>