- open the attached document
- open a new XML form document
- from the Data Navigator of the first document, drag and drop the
  "instanceData/newElement" element into the second document
=> a control for this element is created
- from the Data Navigator of the first document, drag and drop the
  "instanceData/options/@enabled" attribute into the second document
=> a control for this element is created
- switch off the form design mode in the second document
- verify that upon un/checking the "@enabled"-checkbox, the "newElement"-control is
  enabled or disabled
- save and reload the second document
=> the connection between the check box and the input control is lost

fs->lo: I assume the problem here is that drag'n'drop across document bounderies
does work at all. We should probably prevent this, since AFAIK we have no
concept for bindings pointing to an XML tree in a foreign document.