Sell / purchase items from NPC not working with character's window opened

Bug description:
It's impossible to sell or purchase items while the character's attributes window is opened.

How to test:
While in town press "C" to display the character's window. Then click on the NPC using left mouse button and choose "Sell items" or "Purchase items". If you try to sell items, both inventory and shop windows shortly appear but immediately close and nothin happens. If you try to purchase items, both windows open but you can see only your inventory and not the NPC's offer.

Hoping this bug haven't been reported yet. If it already was I apologize :)