HeNCE graphs are drawn in the large initially empty segment in the lower left of the htool window. The mouse is used to draw nodes and arcs.
To draw a node, you must select the type of node you wish to draw by clicking the left mouse button on one of the icons to the left of the drawing area. The selected icon will become highlighted. Then, click the left mouse button on an empty area within the graph drawing segment of the window. A node will appear. The node type selection will remain active until it is changed by clicking on a different icon. The meaning of the different icons will be discussed below.
The meaning of clicking a mouse button is obvious. Press the button and immediately release it. To ``drag'' with a mouse button, move the mouse cursor over an object, then press a mouse button and hold it down. Move the mouse, while continuing to hold down the mouse button. and then complete the drag by releasing the mouse button.
To draw an arc from one node to another, drag from one node to another with the middle mouse button. The arc will appear. There is no way to create intermediate points on arcs; the arc must go straight from one node to another.
Other graph editing operations involve holding down a modifier while clicking or dragging with the mouse. For example, to move a node, hold the shift key down and drag the node with the left mouse button. To move an arc, hold the shift key down and drag the arc with the middle mouse button. Table 1 summarizes.