Why can't I see the listed button? It can only undo the last close tab with a click.

limited : 10 items only. It's not enough

Works well so far. Can be configured up to 25 history tabs and up to ~ 600px width. Not sure if it's really 600px though.
What is missing is the ability to middle click a history item and have it open in a new tab while the pop-up remains open (do not make it close when we middle click, if you add the middle click option :) ).

So, I'm formally requesting the middle click approach so that I can open multiple tabs without having the pop-up close on me.

EDIT: Now that I have used it more. It's actually pretty bad. It doesn't show all the previously closed pages. Towards the end of the list it shows random pages from the history and not in order of recently closed.
I don't trust using it.
It sometimes also has a layout problem and shows the last item overlapped by another item and I can't press on it.