Drilling Down to Underlying Objects
You can drill down to a specific object via the HMI Object Explorer or on the HMI page.
On the HMI page:
To drill down to an object that lies behind an object, right-click the object in the foreground and select 'Drill Down > Underlying object/shape' from the context menu. The underlying object is selected in the HMI page and its properties are shown in the properties window.
Using the HMI Object Explorer:
If the HMI Object Explorer is not visible, click the 
button on the HMI page editor's toolbar.
Click the object in the HMI Object Explorer. If the desired object is a member of an object group, expand the group by pressing the Right arrow key or clicking the Arrow-Right button to the left of the group name.