This demo applet shows a diagram, which was made with the Net Sample Application.
You can move network nodes and links around on the drawing area with your mouse. When you select a network node, handles appear, which allow to link it to another node. Clicking at a network link also shows handles which allow to connect to another node. Double clicking at the connection line of a network link adds or removes a point to it.
The first toolbar at the bottom of the applet contains the creation tools. Select a creation tool, and then press the mouse button (and drag) on the drawing area to create a network node. To create a network link, after selecting the link creation tool, press the mouse button on a node, and then drag the mouse pointer to another node. The cogwheel on the right opens a popup menu.
The second toolbar at the bottom of the applet contains attribute tools. Select a figure in the drawing area, and then use an attribute tool, to change the appearance of a figure.