[news.eclipse.tools.gef] Expand & Collapse effect

[katelin@xxxxxxxxxx (Kate)]

Could any one give me some ideas how to implement the following scenario? 
thank you in advance

I have models structured like this

-- main node
-- branch node A
-- branch node B
-- branch...

main and branch nodes are not parent-child. one main node can connect to 
several branch nodes.

for making the diagram look nice and neet. the main node is displayed all 
the time but the branch node is shown only when needed. 
I want to place a switch on the main node, something like plus sign. So 
the users can switch to show branch node or not.