Hi Chris,
You can take a look at this script:
Save it on your HD and drag-and-drop to Rhino vport to install. The command “DIG_SelectObjectsLayers” will become available.
You can assign it to any button or keyboard shortcut - if you simply want to select the layer of selected object (or layers of selected objects) the macro would be:
DIG_SelectObjectsLayers _Enter
There are some other options available and you can create them with similar macros (select all objects on layers of selected objects, also undo layer selection if you just want to take a look and get back to previous state). The script should be smart enough to expand all layer parent layers so the nested layers get selected as well. I use it all the time as a handy keyboard shortcut.
PS. This is for Windows only. I am guessing Pascal may have Python version that would work on both systems.
hth,
–jarek