Here is some information from the walkthrough that might be helpful:
The inventory is accessed by right click of mouse or by pressing the I key on the keyboard. Items in inventory can be taken by highlighting the item in inventory, click 'use' closed fist icon, move the cursor to game screen and click on the area the item is to be used. To combine items in inventory, highlight first item, click on combine button at top left of screen and then click on the item you want to combine with. The eye icon in inventory is used to examine the items closer. Additional info about the item might be seen at bottom right of the examine window.
I don't think this really answers your question, though, so we may have to wait until someone who remembers the specifics comes along. Now I understand that this is more of an interface question than a gameplay question.