Closing 128 "new" documents in Preview

I opened 128 .png files in Preview, hoping to use it to create a PDF out of them. I think this was possible in earlier versions using the 'New from clipboard' trick. Now I'm on Yosemite. So I copied all of the files to the clipboard, created a new document, and no, it's not possible to make a PDF out of it. (The 'Print' option works, but creates a PDF inflated 3 times in size.) Now I try to close the newly created documents, and apple wants me to click 'Don't Save' 128 times manually?!?!? Most of the time waiting for the slooooooow animations for the dialog. Any way around this?