MACROMEDIA DREAMWEAVER 8-EXTENDING DREAMWEAVER Manual page 247

Returns
Dreamweaver expects a Boolean value:
Example
function showif()
{
var retval = false;
var dom = dw.getDocumentDOM();
if(dom)
{
var view = dom.getView();
if(view == 'design')
{
retval = true;
}
}
return retval;
}
if the item appears;
true
otherwise.
false
The toolbar command API 247