selectionChanged()

Description	Called when the floater becomes visible, and whenever the selection changes (when focus switches to a new document, or when the insertion pointer moves to a new location in the current document). This function should be defined only if the floater must track the selection.
	Note: Only define `selectionChanged()` if you absolutely require it, because its existence impacts performance.
Arguments	None.
Returns	Nothing.
Example	The following instance of `selectionChanged()` shows a different panel (layer) in the floater depending on whether the selection is a script marker or something else:

function selectionChanged(){
  /* get the selected node */
  var theDOM = dw.getDocumentDOM();
  var theNode = dw.getSelectedNode();

  /* check to see if the node is a script marker */
  if (theNode.nodeType == Node.ELEMENT_NODE && theNode.tagName == "SCRIPT"){
    document.layers['blanklayer'].visibility = 'hidden';
    document.layers['scriptlayer'].visibility = 'visible';
  }else{
    document.layers['scriptlayer'].visibility = 'hidden';
    document.layers['blanklayer'].visibility = 'visible';
  }
}