Layers and Multiple Shapes

[oldbuickguy]

I'm a newbie who is using Visio 2007 to draw 2D mechanical assemblies.  Each component is on a separate layer. 

I'd like to convert components comprised of line, arc and circle shapes into solid shapes so when shapes are displayed the components in the front mask the background components.  I have attempted to use Shapes>Operations>Join to convert the components to solid shapes to no avail.  See attachment 'Prior to Shape-Operations-Join.bmp'.

After I have the shapes defined and filled, is there a way to identify a layer's position in the stack so the displayed image reflects line of sight.

[Paul Herber]

Join loses all the layer information. It wouldn't make much sense to keep it once the shapes are joined.

[oldbuickguy]

Thanks, Paul.. 
I used Shapes>Operations>Combine to get from a 'segmented' object to an object with a solid outline that could be filled.  i.e. Filled Slots attachment.  The kicker was that I'd used 'line with extensions' with '3pt. Arc' for the original composition, and the ends didn't snap to form a closed object.  I did some reading, found Drawing>Line Tool and changed the occurrences of 'line with extensions' and then Combine gave me a closed object.

Second attachment, Filled Eccentric, is a similar case, but entirely created with segments of '3pt Arc'. When I used Combine to close the object, Fill uses an interior perimeter as it's boundary rather than the actual object's perimeter.  I haven't determined where the interior perimeter is defined. Is there a method to decompose the objects on the drawing page identified by the purple boxes shown by Edit>Select All, to perhaps identify un-displayed objects involved with the eccentric before, I perform the Combine? 

TIA,
Jeff