What do I need to change to make the loot window NOT closed by ESC?
 

I use the custom fetish interface and its great, but as a tank I tend to use ESC a lot, particularly when using the keyboard to select the "next mob" and it annoyingly selects, for instance, a patch of roots next to me, thus ruining my group's assist mode. People yelling at me makes me an angry tank, and angry tanks break things like Wizards and Clerics.

I am familiar with XML, but not sure what attribute needs to be changed in what file. Thanks :)

Add the property

allowcloseontop="false"

to the window.

You'll also need to search for and remove all occurances of
iscancelbutton="true"

I dont think the loot box has a cancel button.