Late Night With Jimmy Fallon/YouTube screenshot by Chris Matyszczyk/CNET

It all started so well.

Jimmy Fallon called Bill Gates "cool," which hasn't always been the first word used to describe Microsoft's co-founder.

Gates appeared on "Late Night With Jimmy Fallon" and talked about the stunning success he has contributed in the fight against polio.

Ultimately, though, Fallon wanted to talk gadgets. How will computing change?

Gates replied that tomorrow's computers will be able "to see, to listen, to talk, to recognize handwriting."

Gates has always been keen on handwriting and styluses, hasn't he? Though, I wonder how many of tomorrow's generations will even know how to hold a pen, never mind use one.

As Gates continued to explain his vision of a multiscreen world, Fallon became aware that he'd committed an on-screen faux pas.

He noticed that Gates was looking over to his laptop. Oh, of course, it's a MacBook.

Suddenly, Fallon's features coursed with (fake) shame. "This is very disrespectful," he said, as he quickly tried to close the MacBook and remove it. The Apple keyboard and mouse had to go too.

Gates merely smiled.

I fancy that this may not have been a big deal to Gates at all. It's a scenario that must have been performed in his life many times.

Moreover, in recent years, Gates has shown a highly developed sense of humor. His very underrated Microsoft ads with Jerry Seinfeld were an utter breath of fresh personality.

And on the Fallon show, he promoted his GatesLetter.com report on the benefits of foreign aid with an amusingly self-deprecatory video. (See below)

Just over three years ago, his wife, Melinda, said that though their kids had asked for them, there were no Apple products allowed in her house.

Gates continues to champion Microsoft at every opportunity, but here he didn't even bother to suggest that Windows laptops are more advanced.

Perhaps he's got more important things to think about. Such as who on Earth will be Redmond's new CEO.