KDE 4.1: Don't look back

Vijay Patil asked me to explain the application browsing component, so here it is:

At first, you get a panel with two columns - Favourites on the left, and application categories on the right.

When you choose a category, the Favourites column is replaced by the application categories, and the currently selected category is opened in the right column. (can anyone guess what is the ratio between left and right columns here, but without looking at the code?) As you can see, you get a breadcrumb bar above the list.

Now, there are two options for ‘what should happen when a subcategory is chosen’. One would be to hide the left column again like in the previous step, and the other is just to shrink the leftmost column like in the screenshot:

Later (the one in the screenshot) way is uglier, but more useful (for me, that is). Since I can not make up my mind about it, it will be configurable.