New Alt-tab: Up/Down arrow interaction
The use of the arrow keys in the Alt-tab switcher is somewhat weird, as left and right can be used at two levels; it would probably be more logical for the user if the keys operated as a grid/matrix, as for scrubbing any other type of menu stack:
1. Alt-tab to open switcher
2. Left/Right (Tab, Shift-Tab) to switch between groups
3. Up/Down (no equivalent) to switch between individual windows in a group;
The operations would then become completely reversible; Up/Down would rotate between window items (currently); pressing Left/Right would move to the next or previous Alt-tab group.
(nb. This pattern is logical and follows the pattern used by all major operating systems for menu-traversal; with possibilities such as "Sub-menus" expanding with more content).