It just pastes an empty space. It doesn't matter if you're pasting just " " or if you're pasting a big, long page of text that happens to have a " " in there somewhere, dabblet will seek it out, and remove it, and replace it with a space.
As you may know, does not equate to 6 empty space in html. But if I pasted " " in to dabblet, it would turn in to 6 empty spaces, and therefore only actually display as one space.