Sorry if its posted somewhere ,I did search , just getting over a sickness bug so excuse sounding lame .
I like the look of this UI for my druid. I was looking at where I might setup my keybindings , is this via wow interface , or does nUI come with its own method.
I think, if you hover over the button in question it will bring up a message on how to keybind. If not then the normal option keybinds should include an nUI section.
If i'm not mistaken the way to bring up the key binding menu is ctrl-alt right-click on the slot and it will pop up a window in which you can bind or rebind a key to that bar slot. AFAIK it works with all the bars that nUI offers.