I can’t even find this one in the Keyboard Shortcut list provided in the User Guide of Expression Blend, so I made up a name for it: The Artboard Objects List:
Known from several drawing programs, this list shows the objects under the mouse cursor when you hold Ctrl and Click the Right Mouse Button. It highlights the currently selected object and lists all other objects overlapping each other from the topmost at the top of the list to the one at the bottom on the bottom of the list. Notice that the order of this list is opposite to the default order in de Objects and Timeline Panel (when you have not changed the order of the panel using the Sort by Z-order option at the bottom left of that panel). Actually, this order is logical for what it shows: the stack of objects in the Artboard under your mouse cursor.
Notice also the option to Pin or UnPin the Active Container. This makes is easier to insert newly created objects in a container like the RegularPolygon Shape in the Grid here inside the RadioButton…