I have a few ideas for encouraging arrangements of definitions to have more life in the sense of Christopher Alexander:

• quantize the x axis to discrete columns
• don't force a single grid; that can look boring. Each node occupies 600px of width, so quantizing at multiples of 100 gives us 6 possible arrangements.
• always position new nodes within the current viewport
• always position new nodes at least some amount of padding above to give the node above some room to grow
• forbid overlap
  • moving a node against another should push the other node as well
  • I want a node to yield some resistance, but I don't want resistance to grow linearly by the number of nodes pushed