When you hover the mouse over the number of items in your storehouse it gives you the exact number you have.
I would like to see this in the trade office as well.
When looking at a deal, I would like to hover over the icon and know how much I currently have in my stores. Then I can evaluate if I should take a deal or not.
As it is I have to close the TO, open my storehouse check the number, go back to TO, find the offer again.