or download this
Save as Text Doc "boo.txt" -> saved as boo.txt /\.txt\z/==1
Save as Text Doc "boo" -> saved as boo.txt /\.txt\z/==0
...
Save as All Files "boo." -> saved as boo. '.' ne ''
Save as All Files "boo.pl" -> saved as boo.pl '.pl' ne ''
Save as All Files "boo. pl" -> saved as boo. pl.txt '' eq ''