From OpenJUMP Wiki
To draw a feature first check out that the layer is on editable mode on Layer Menu.
This opens the Editing Toolbox where the main drawing tools are.
You can choose the tool for drawing polygons, lines and points.
Example: Drawing a polygon
- Click on Draw a Polygon on the Editing Toolbox. This tool allows to draw polygons on the Layer View. It is also used to draw holes on a polygon (see Editing Toolbox for more details).
- The mouse arrows turns to a pencil shape . User can draw a polygon on the screen by clicking on the left button of the mouse at the cornes
- To stop drawing and to close the polygon double clik on the left button of the mouse. The polygon will be displayed with a neutral colour (usally green) or with the colour of the attribute