Create a backlog list.
Let's do this project with Scrum.

- Dummy main widget & build system
- Test system(?)
- Menu bar: save/open file, quit.
- canvas with root element
- element widget
- connect/disconnect emelent (line widget)
- move element
- element, line widget properties (rigth click menu)
- moving with cursor keys, inserting / deleting with cursor keys
- icon
- taskbar app