Comment 2 for bug 419270

So for version 2.0 I can think of three design solutions:

1. An extension of the current behavior. Departments with no available items are still displayed, but navigating to one shows only the centered text "No items are available in this department."
    + Simple.
    + No performance penalty.
    – Frustrating ("why did you even bother showing it?").
    – Cluttersome for users in corporate etc environments if they have been granted permission to install items from existing software sources but not to change sources ("this department is always empty and I can't change that").

2. The lobby screen is empty except for a spinner and progress bar, until the Store has surveyed all departments and worked out which ones have items available. Then all non-empty departments are displayed at once.
    + Appropriately cinematic.
    – Slow: even if you want to choose something from the first department, you have to wait until all of them have been queried.

3. The departments are surveyed in alphabetical order. As each is surveyed, if it is non-empty it is displayed in the “Departments” section. As long as there are departments remaining to be surveyed, a spinner is displayed in the spot where the next department will appear.
    + Minimum delay.
    – Future versions of the Store will have more than just “Departments” on the front page, and the lower sections will jump around nastily if the departments appear incrementally.
    – Especially jerky if the window width and software sources are such that the spinner for surveying “Other” takes up a line by itself, only to collapse when the Store discovers there are no items in the “Other” department.

Are there any other solutions? Could there be some way of caching the list of non-empty departments, invalidating that cache whenever the list of software sources change?