[Bug-gnubg] Question about the Hint Window Evals

[XXX]

In the Hint window (for checker play) there are buttons marked
Eval ... 0 1 2 3 4
Where can I toggle the pruning on/off  for the 2-ply button?
At the moment I have Settings-Evaluation (checker play) set to 2-ply with 
pruning OFF

Occasionally when the filters are not wide enough to catch a move I want 
evaluated at 2 ply in the hint window, I select the move and hit the 2 
button. But this seems to give me a PRUNED eval.

Where can I set this to prune OFF?

Thanks