[xmonad] How to configure TwoPane to this way

[Chengqi Song]

Hi All,

I like the TwoPane layout, but need to special configuration:

Suppose we have windows A, B and C. Now A is on left pane and focused, B is on
right pane, C is not visible: 
 (A) | B, C

Now I need a special HotKey, when triggered, it keeps B untouched, just switch
between A and C on the left pane.

And I also want another HotKey to switch between left and right pane.

Is that doable?

I need it a lot, thanks very much.

best
lars