Using the default theme for Moodle 2.8.5 (using MAMP on my laptop), the Facebook Comments block does not resize properly, even if the browser window is maximized. (see screenshot below)
The biggest drawback is that it hides the comment button. You can only access the Comment button to submit comments if you type enough text to force the block to scroll right. Even then, as soon as it wraps to the next line, you lose access to the button again.
Ideas? Do I need to log in as an admin to fix?
PS I see this question was asked in early March, with no response.