Here are two minor bugs with the interface that I've come across during my playtime in DA 1.6.

First, spy placement:

1) Get a spy
2) Open the Domestic Stats
3) Go to the Espionage tab
4) Choose to place the spy using the button in the bottom left
5) This will close the domestic stats menu and let you place the spy, do so to some shmuck civilization somewhere (I recommend Drengin, cause I always play Altarians and enjoy hurting them)
6) Click on Domestic Stats again

Nothing happens. The second click will open the Stats menu like normal, but the first one is apparently considered to be closing the menu, but the menu is already closed and so the game doesn't do anything.

Second, active Domestic Stats:

1) Start a new game or load a game
2) Click on the Domestic Stats button

Notice that although the Economic tab's contents are displayed, the Economic tab is not the active tab. In fact, no tab is active. Clicking the Economic tab makes it blink, but it still isnt' active. Clicking an inactive tab (Trade or Espionage) will make that tab active, and the bug will be gone for the remainder of the play session. If the Domestic Stats screen is brought up using the Espionage button in the bottom left, the Espionage tab is automatically highlighted and so the bug does not occur.