Maybe not only the Staoshi client should have an option to hide the balance.
o show balance
o show balance after click
o show balance after password
All clients have the balance as the most prominent feature which is bad in a face to face trading situation.
The rubber hose always wins. Hiding your balance means that you have something to hide. If the guy was going to rob you when he sees your balance, you should also assume that he is going to rob you when he sees that you hide your balance.
If you are putting yourself in physical danger, use a different wallet, one that only has the amount needed for the current trade.
