- bidirectional port/line
- load/save map
- data structure
- node add/del with reponsive show/hide
- scale links
- line animations
- particle flow
- line broken
- link back
- one way link
- node animation
- node down
- node up
- edit/monitor mode transition
- event list
- time line
- object change diff
- playback
- panel open/close show/hide
- event list panel
- node list panel
- API verfication
https://medium.com/@poyingchen/svg-icon-custom-element-4d60af66466c