Handles.DrawLine  

static function DrawLine (p1 : Vector3, p2 : Vector3) : void

Description

Draw a line from p1 to p2.

Draw Line in the Scene View.

// Draw lines to the connected game objects that a script has.
// if the target object doesnt have any game objects attached
// then it draws a line from the object to 0,0,0.

@CustomEditor (ConnectedObjects)
class ConnectLineHandle extends Editor {

    function OnSceneGUI () {
        for(var i = 0; i < target.objs.Length; i++)
            if(target.objs[i])
                Handles.DrawLine(target.transform.position, 
                            target.objs[i].transform.position);
            else
                Handles.DrawLine(target.transform.position, Vector3.zero);
    }
}

And the script attached to this Handle:

//ConnectedObjects.js

var objs : GameObject[] = null;