Pipeline Browser Requirements

• File dialogue-like selection. Anything on the pipeline browser should be selectable by click or click-drag, modified by Shift or Ctrl keys, per typical file browser selections.
• Cut, Copy, Paste support
  • Internal - can copy or 'instance' arbitrary groups of items. For example, pasting a subgraph onto a node would paste that subgraph onto the node as a direct connection. Pasting two separate subgraphs onto a node (at the same time) would paste two new subgraphs onto the node.