1. Activating the second tab leads to its header having the focus (correct).
2. Using the tab key, the focus changes to the second tabs content (correct).
3. Using "Shift + Tab", the focus changes back to the header row, but to the first tab header (incorrect, the second tab header should be focused).
4. Using the right arrow key, the focus changes to the third tab header and this tab gets activated (actually correct, but confusing considering the previous point).

The problem is caused by the tab index of the tab headers not being updated properly. The first one seems to have 0 at all times, while all others stay at -1. Instead, the active tab header should have tab index 0, while all others get -1.