A Long expression that specifies the index of the layer.
By default, the Index property is automatically updated by
the control, as soon as the user adds / removes layers to the control. The
Index property is read-only and zero-based, which indicates that the layer
with the Index property 0, it is the first layer, while the layer with the
index Count - 1, is the last layer in the
control ( in z-order ). The Key property retrieves or sets the layer's key.
The Item property of the Layers collection
accesses a Layer giving its index or key. The LayerFromPoint
retrieves the index of the layer from the point ( only visible and selectable objects are included ).