I tried Mousepad then uninstalled it because printing wasn't working. It turns out this happens (at least in Fedora) if xfprint is not installed. If xfprint is not available, the error should at least be nicer than something about a pipe not working!
I'm closing this bug since Mousepad has been rewritten and doesn't depend on xfprint anymore. If you find any bug related to printing, please report another bug.