When I try to alt-tab backwards (with shift) - elementary switches to the end of stack.
E.g.
- I have opened 5 windows.
- Switched to the 4th one using alt+tab 3 times.
- Pressed alt+shift+tab. Now I am on the 5th window and this window is now in the beginning of the stack. If I try to press alt+shift+tab once again - it start switching windows from the end of the stack.