Filter: Organic groups: Current group ?

I have a group node type Bar that references other nodes of type Foo (NOT group posts) via cck nodereference (field Foos).
The nodes of type Foo are not group posts. The nodes of type Foo do not know whether they are referenced by group nodes Bar
My view has to list all the Foo nodes for the current Bar group.
Here is what i did :
Filter : Node type is Bar (group)
Relationship : Content : Foos
Row style: Node -> use relationship Foos

How to tell the view to filter on current group ? i have tried using agument group nid but i am using purl with spaces to make groups' path aliases

Any help would be much appreciated !