Problem with frontend media library

Hi,

I want to allow some users on a WP site of mine to access the media library from the frontend to set the post thumbnail. I've got it working in general, but when an image is selected you can then click on a pencil item on the thumbnail and it pops up with this box

Top left has two grey squares with nothing in, and there's no submit or close button (except for the top right X). This is not friendly to users. Is this how it should look? Is there a way to change it or to remove the pencil so users can't see it?

Thanks