Suppose you take a potion of Fortify "x"

Could someone tell me if time continues while idling in the following interfaces;

Smithing interface (forge and/or wheel).

- - Could the fortify smithing potion expire before you can craft an item?

Enchanting interface.

- - Could the fortify enchanting potion expire before you can enchant an item?

Barter interface.

- - Could the fortify barter potion expire before you can buy something?

Dialogue interface ( same as barter? )

- - Could the fortify persuasion potion expire before you can select the dialogue choice?

Update: Smithing and Enchanting definitely expire in the interface.

What about barter / persuasion? Does time freeze when you're talking to an NPC?

You can determine this by noting whether the environment continues to move around the player while they're in the menu/interface. For example, the smithing, enchanting, and dialogue interfaces all happen in real time - other characters can talk to you, walk around you, or even interrupt you while you're in those menus. I believe the barter menu freezes time entirely, so the potion shouldn't expire -- but I don't have access to the game right now, so I can't confirm that for certain.