The primary purpose of an icon is to visually represent data to a user. Typically, this data will have a meaning such as “this needs attention” or “click here when you want to save”. Since the icon is supposed to represent a single thing, it’s rare to see something like this in a shipping product.
I can’t recall the last time I saw the same icon appear twice on the screen, with different actions attached to it. Sure, one action is for the tweet and one is for the webpage URL – I get that. But that is a really subtle distinction that most users won’t be savvy to. Think of the joy of trying to explain that to one of your non-technical friends.
I can only assume this will be different in the next release.

I was clicking those various buttons trying to hide that sidebar and noticed that they did not match the normal respond, forward etc….
Unfortunately I could not find a close icon and the swipe to the right only partially moved the sidebar…
It never ceases to amaze me how even the big software companies put oit products that dont conform to any design guidelines, standards or are just full of plain old bugs – dont these guys implement any end user testing/QA procedures any more?