More screenshots.  Video Tutorial below...

Video Tutorial #1

Covering: Basic Usage of the Pynsource application including creating classes and joining them together. Editing classes, laying out diagrams, reverse engineering existing Python source code. Changing line types, between association, generalisation (inheritance) and composition. Switching between main UML view, PlantUML view and Ascii view - the latter you can paste into your source code!

Duration 4 mins.

More video tutorials coming.
Note: Dragging to connect classes is a Pro mode feature. The community edition can also join boxes albiet via r. click menus.
P.S. Sorry about the robot voice in the video - it just makes it easier to produce and edit.