When you start attacking your opponent on the basis of his height, you have descended to Trump's level.
This is the clearest indication yet that Jeb is getting desperate. His numbers are rising in New Hampshire and nationally, though not in Iowa. He's not cooked yet.
But if he keeps this kind of thing up, it won't be long before we can completely write him off.
Trump can get away with this stuff because bad manners are his brand. We expect more class from any member of the Bush clan.