The use of the described drawing tools depends on the selection of the active mapping class. Some of these tools can be used for several mapping classes – e.g. for area and line mappings. Caution: When drawing an area, please note that it can only be closed if its outline is not intersecting itself. Note: If you press the SHIFT-Button whilst drawing only vertical and horizontal lines will be drawn (ortho mode). Note: Below Project>,Project settings you can define and activate a Snap Radius. Drawing a freehand polygon, it will be automatically closed whenever you undercut a preset distance to the start point. Caution: If the area intersecting functions are applied to an area, which consists of cubic splines, these splines will be converted into freehand polygons. Note: You can combine the above mentioned drawing tools within one mapping element. When drawing, press the TAB-key to change between different drawing modes. Source.