Rick, no not break, just to be able to add filters, for example with panes on the left, just like you can do today by filter in the upper right search window.
It's still not clear how this would work. "Just to be able to add filters" implies categories and panes would be defined separately and there would be no overlap. In other words, a category used in the browsing chain would not be available as a "filter" in panes. That would avoid the questions I raised, but it isn't a reasonable restriction.
Maybe an example will help. Let's say my primary Audio view is a Genre-Filters-Artist-Year-Album-Rating Panes view ("Filters" being a set of search lists, like single/multiple, recent, duplicates, etc.). I currently have to use a separate Genre-Artist-Album Categories view to browse by thumbnails. You seem to be suggesting a change that would allow me to add Filters, Year and Rating to the Categories view as panes. That would work, but it would just be a Categories view with some filters tacked on. It wouldn't come close to replacing my primary Panes view.
I would prefer a "Panes + Categories" to a "Categories + Panes" solution. That is, the panes would be configured as they are now. There would be an option for each category to "include in browsing chain" that would define the "+ Categories" browsing feature. As to how that behaves when selections are made in the panes, perhaps there could be two options:
1. Independent—Making any changes in the panes will change the results, but the categories panel will remain at the same level in the browsing chain. For example, if it's currently showing the albums of one artist and I change the genre in panes, it will stay at the album level, but will now show all albums for all artists in that genre.
2. Dependent—Making any changes in the panes to a category included in the browsing chain will result in the categories panel jumping to the next category in the chain. Using the same example, it would jump back to Artist—showing thumbnails for all the artists included in the selected genre.
Maybe that choice is pretty much the same as the existing "Filter in both directions."