These are the steps that are taken when selecting the tool:
the user selects a link to draw between two nodes.
the linkableFrom properties on all nodes will be set to true (default false)
the user clicks on a node to draw a link
a call will be done to the database to check whether a link can be made between the nodes (this is done for every node), if a link can be made between the nodes, the linkableTo property will be set to true.
the user drags a link to another node which can be linked to
the new link get displayed with the right template model and works just like every other link, except that it isn’t added to the linkDataArray, also the linkdrawn event is triggered.