Is it possible to extend the visibility rules? I would need rules with more dependencies.

To implement more complex rules, it is possible to introduce rules into ActionScripts using the bfToggleFields() method.

Note: To use this method you must have previously defined at least one dummy visibility rule like:

 turn on element mydummy if yourdummy is something

Example for a script into a checkbox element:

function ff_checkbox_action(element, action) //where checkbox is the name of the checkbox element
{
     switch (action)
     {
          case 'change':
          if (ff_getElementByName('checkelem').checked && 1==1 ) //here you can add further dependencies 1==1 will always be true :D
          {
               return bfToggleFields('on','section','sec2',bfDeactivateField);
          }
          else
          {
               return bfToggleFields('off','section','sec2',bfDeactivateField);
          }
          break;
          default:;
     } // switch
} // ff_checkbox_action

 Example for radio and checkbox groups which need a special code in order to read the current value:

function ff_radioelem_action(element, action) //where radioelem is the name of the radio group
{
     switch (action)
     {
          case 'change':
          vals = '';
          opts = JQuery("[name=\"ff_nm_radioelem[]\"]");
          for (o = 0; o < opts.length; o++)
          if (opts[o].checked)
          {
               vals = opts[o].value;
          }
          if (vals=="yes") // here you can add further dependencies
          {
               return bfToggleFields('on','section','sec3',bfDeactivateField);
          }
          else
          {
               return bfToggleFields('off','section','sec3',bfDeactivateField);
          }
          break;
          default:;
     } // switch
} // ff_radioelem_action