If you look closely at the Vista Explorer breadcrumb bar, you will notice that when you toggle a context menu, the menu item text is left-aligned with the text in the breadcrumb item immediately to the right. It looks something like this:
...where the menu item headers for 3A, 3B, 3C, and 3D are horizontally aligned with the 3A breadcrumb item header. Can this be implemented in the next release of Navigation for WPF? It should be fairly straightforward--I implemented this functionality myself in an open source breadcrumb on CodePlex.
+-+---------+-+---------+-+----------+-+---------+
|>| Level 1 |>| Level 2 |v| Level 3A |>| Level 4 |
+-+---------+-+---------+-+----------+-+---------+
|x| Level 3A |
| | Level 3B |
| | Level 3C |
| | Level 3D |
+-+----------+
^
Left-Aligned