Rev Toolbar "Group" button - How does it work?!

[tim at leaf25.com]

Hi All,

I am trying to get the same effect as the Rev team have done with the 
"Group" button on the top toobar.

When you click on an object with the "pointer" tool, the Group button on the 
toolbar immediately becomes available. Likewise, when you deselect the 
object, the Group button becomes disabled.

How can I do this in my own stack? I can't work out what message to trap, as 
it seems that much fewer messages are sent when the "pointer" tool is 
selected, as compared to the "browse" tool.


Many thanks,


Timothy Due 
http://www.leaf25.com