var uiElement1 = // Some Element, lets say texture
var uiElement2 = // Some Other Element lets say texture
var uiElementContainer = // Some panel which contains all ui elements
var guiCamera = GetComponentInChildren<Camera>();
var transformedPosition1 = guiCamera.WorldToScreenPoint(uiElement1.transform.position);
var transformedPosition2 = guiCamera.WorldToScreenPoint(uiElement2.transform.position);
var line = VectorLine.SetLine(Color.red, transformedPosition1, transformedPosition2);
line.vectorObject.transform.parent = uiElement1.transform; // Add under uiElement 1 to clip when it moves off the panel
line.Draw3DAuto(uiElementContainer.transform);
line.lineWidth = 2;