Think of an "editing" mode without layouting

[GoogleCodeExporter]

What steps will reproduce the problem?
1. live editing does not work, since intermediate node states can crash
most layouters

What is the expected output? What do you see instead?
- Think of an editing mode, that does not do any layouting, but
just adds nodes and allows to link them, or remove nodes and links.
- When switching back to a layout mode, do a sanity check on the graph
- Certain layouters will not work with all types of graph.

Please use labels and text to provide additional information.

- Ok, during the "graph checking" phase, the result could be
  expressed in certain flags like
  * disconnected/connected
  * tree
  * forest
  or something. 
- Depending on the result only certain layouters will work
- provide a default layouter, that ALWAYS works (maybe it does nothing,
  or a grid, or something)
...

Original issue reported on code.google.com by spo...@gmail.com on 21 Mar 2008 at 4:44

[GoogleCodeExporter]

if create a topology graph by edit tool, it must separate present mode and edit 
mode, which means draging and droping node and linking two nodes to draw a line 
between of them, then create the xml data structure to describe the graph, and 
this 
xml data is just the data source of topoplogy graph.

Original comment by lwz7...@gmail.com on 25 May 2008 at 11:44