I'm running the same version of AdBlock, and I was just able to whitelist a website, so I'm wondering if you think text entry is disabled because the drop-down has got pre-entered text?
Clicking in the drop-down's field gave me a cursor, and the default text disappeared as soon as I began typing, and VOILA! (Not especially intuitive.
)
By the way, it took some searching to figure out how to reverse my addition to the whitelist, but I finally found it at the very top of the "Manually edit your filters" pane.
