Did Bill Gates steal the GUI concept from Steve Jobs?

So, I have a pretty long and involved answer for you which I believe will allow you to understand the answer to your question in a lot more depth, as what happened back then is honestly a long and complicated story. It's not just "did Gates get a hold of Apple's OS design and then copy parts to save himself time and work making his own", which in short yeah he basically did, but as said it's a lot more complex and interesting than that, as the real whole truths usually are!

I immediately thought of "Pirates of Silicon Valley" (which I saw once and only shortly after it was made, quite a while ago) as well when I saw this question. I haven't seen the recent Job's movie, but I have to think that "Pirates" was more accurate and less biased. While we can look up a lot of historical facts regarding the more general question did Gates steal from Jobs, I'm sure some of it isn't a matter of public record and is only in the minds of the late Jobs and Gates and some of their associates and contemporaries. We'll never know the entire truth regarding all of the intimate details, but what we do know in addition to the facts already listed here is that Jobs felt taken advantage of, and an idiot for, allowing Gates into Apple in the beginning and giving him a tour of their developments, showing off the mouse that his engineers came up with that worked with the GUI interface they were designing. The two paired together in what Apple had created were unique at that time. As pointed out, Apple didn't invent the mouse, nor the concept of a GUI, but had made a unique OS on a computer they created that employed a mouse. That was their own, what they had put together. And Steve Jobs was showing off and didn't realize it wasn't a good idea to give someone like Gates intimate knowledge of it all.

Well, remember, Steve WAS a hippie who was previously living on a commune with his wife, he wasn't yet the ruthless capitalist he turned into. I majored in CS in college a long time ago, and I remember doing a very long and in depth paper on the subject of Steve Jobs, Steve Wozniak, Ronald Wayne, and the birth of Apple and their early history and relationship with Bill Gates and Microsoft. I remember a good deal from way back then (we're talking more than 20 years ago) and I believe that that fateful day Gates was given basically an all access tour of Apple, he definitely saw dollar signs replace his glasses and couldn't believe his luck to be seeing what he was. (As a side note, he was invited in on the premise of developing software for Apple, more likely a reconnaissance and intelligence gathering mission from Gates' point of view, but Steve was just so excited to show off his cool stuff, he showed him way more than he needed to for just the strict purpose of software development, and Gates was not made to sign any contracts or agreements regarding what he was shown.) Code, blueprints, schematics, concepts, hardware in development, like EVERYTHING you would never want your rival to see in business. But Gates wasn't really a rival at that point, and Jobs was a real big dreamer then, an idealist, didn't care much about money, and wanted to change the world and make it a better place with his ideas about PCs and technology - remember of course, basically every large company laughed at him regarding the idea that people would ever want personal computers on their desks at home. I never knew Steve or met him, so I can't say how little money actually meant to him in these plans, but the point is that he was driven more by his idealism and changing the status quo and being the David vs. the Goliath that was IBM, Xerox, Ma Bell, the other massive technology companies of the day.

Yes, yes, we all know that this man changed radically over the decades. Off topic though, but just acknowledging that he became the polar opposite after he was fired from Apple when the company nearly tanked in the 90's because he wasn't a ruthless capitalist businessman, and left for quite some time and came back a changed man with different ideals and motives and philosophies, I am very well aware of that.

So, the whole point is as an avid historian and user from the start of Apple products, I feel I can offer a pretty close to the truth version of events surrounding what did Bill Gates "steal" from Apple and Jobs. He really didn't "steal" anything, it was pretty much naively GIVEN to him. Gate's broke a bond of trust with Jobs in that he promised not to use against Apple and Jobs what he had seen and learned from his unprecedented outsider access to Apple. As far as I know, Gates literally walked out of Apple that day with floppy disks full of code and his head full of concepts and ideas he'd been shown, and maybe even technical write-ups and drawings, schematics, on some stuff. Was it all handed to him, or did he make copies of stuff when no one was watching, when he was left alone? Unsure. Arguments differ on this part from both men. He said, he said kind of deal.

So Jobs felt violated and was angry at Gates for what he saw as clearly ripping Apple off (even if they had already ripped parts of what they had off from someone else originally). Like, you can use this information to help the goal of making PCs a reality in every home and changing how the world fundamentally thinks about them, but don't use it to put me out of business in the process. Sort of the David vs. Goliath mentality, us little guys helping each other out against them, because he saw it as an "Us vs. Them" situation. On our side, our team, or against us, and didn't see Gates as against us. Naive, yeah.

So he was also really mad with himself for allowing Gates to have access to all the stuff he did, in addition to being mad at Gates for "ripping him off". Angry in those two ways.

Gates basically just saw a great niche business opportunity with the creation of PCs for home and office users, and took advantage of whatever he could from whoever he could to achieve this. He got a leg up from being given a personal tour by Steve Jobs himself of Apple's projects. A pretty big one. He gained ideas and concepts, and actual products, and figured out how to exploit them in more successful ways (note I didn't say BETTER ways, just ways that were more successful in business, as I'm not personally saying Gates' created a better OS, just a more popular one via many different means) to make a more successful product and more money, and applied it all to Windows.

How Gates' business genius allowed him to succeed wildly by what seemed a fools gamble and a GREAT deal for IBM, by licensing DOS instead of selling it, is a different story. Once he had the choke hold on the OS bundled on IBM PCs, which was like 97% of the PC market, he went on to Windows and entered the GUI world and that's where our 2 characters have their big moment with each other - Gates getting a tour of Apple from Jobs, of course.

I know that was a much broader answer than you may have been looking for, but I find the whole history of the late 70's and early 80's in PCs with Apple and Windows just fascinating, I hope you do, too. And that this in depth telling of it was interesting to you as well as informative. Who would have ever thought that Apple and Jobs would end up being Goliath by the time he died? Amazing story, but also another chapter in Apple history for another question. And that's that.

At the risk of sounding like a total hippy and/or pedant, it's worth pointing out that one may not really be able to steal an idea at all.

Google definition of steal.

You can copy ideas, but you can't take them.

So in that sense the answer to your question would be no. And they didn't steal them from Xerox either. Even if Gates did copy the idea from Xerox, Xerox still had their idea.

It's worth remembering that the first graphical user interface for IBM-compatible PCs came not from Microsoft but from Digital Research, whose GEM product could be layered either on top of MS-DOS or on top of DR's own CP/M. Microsoft were probably less worried about Apple as a competitor than about Digital Research, who were well placed to steal the whole market for operating systems for IBM-compatible PCs.

There was another movie called The Pirates of Silicon Valley starring Noah Wyle and Anthony Michael Hall as Steve Jobs and Bill Gates, respectively. That movie also touched on the intrigue of the dispute between Apple and Microsoft regarding Windows. I can't remember the exact quote but it went something along the lines of how Bill and Steve were like burglars who robbed from their neighbor, Xerox in the middle of the night so neither can take claim on "owning" the GUI.

Microsoft was on shaky ground because they were privy to a lot of information about the MacOS while making Office for the Macintosh. But technically they did not violate any agreements with Apple when they released Windows. And neither company is famous for originality, they just take what others have already done and make it a little bit better.

"You're ripping us off!", Steve shouted, raising his voice even higher. "I trusted you, and now you're stealing from us!"

But Bill Gates just stood there coolly, looking Steve directly in the eye, before starting to speak in his squeaky voice.

"Well, Steve, I think there's more than one way of looking at it. I think it's more like we both had this rich neighbor named Xerox and I broke into his house to steal the TV set and found out that you had already stolen it."

Not fundamentally different to the other answers, but a good retelling and detail here:

A rich neighbor named Xerox

That characterization is not legally accurate. Yes, Apple believed that Microsoft infringed on its GUI ideas, and filed a lawsuit in 1988. They lost. Jobs himself obtained the idea from implementations he witnessed at Xerox PARC. Microsoft did not just use this argument themselves to win. Rather what happened is that Xerox noticed the suit and joined the fray, suing Apple.

The Apple lawsuit inspired Richard Stallman, of GNU fame, to create the League for Programming Freedom in 1989.

A graphical interface with mouse device used for moving a pointer on the screen was demonstrated in 1968 by Douglas Engelbart. This event is referred to as the Mother of All Demos.

Microsoft "stole" the GUI in roughly the same way that every scriptwriter has "stolen" their movies from Shakespeare. Ideas are important, but implementation is everything.

I'll start by saying I haven't seen the movie, so I don't know what it claims. However, I didn't see it because I lived through most of it as a home computing enthusiast, so I already knew the subject material.

The GUI was initially developed as one of many innovative new research projects at Xerox's Palo Alto Research Center¹. Silicon Valley being a small place back then, Steve Jobs got himself a tour one day, and just flat out fell in love with their GUI.

I had three or four people (at Apple) who kept bugging that I get my rear over to Xerox PARC and see what they are doing. And, so I finally did. I went over there. And they were very kind. They showed me what they are working on. And they showed me really three things. But I was so blinded by the first one that I didn’t even really see the other two. One of the things they showed me was object oriented programming – they showed me that but I didn’t even see that. The other one they showed me was a networked computer system…I didn’t even see that. I was so blinded by the first thing they showed me, which was the graphical user interface. I thought it was the best thing I’d ever seen in my life. Now remember it was very flawed. What we saw was incomplete, they’d done a bunch of things wrong. But we didn’t know that at the time but still thought they had the germ of the idea was there and they’d done it very well. And within – you know – ten minutes it was obvious to me that all computers would work like this some day. It was obvious. You could argue about how many years it would take. You could argue about who the winners and losers might be. You could’t argue about the inevitability, it was so obvious.

After this visit, Jobs essentially bought himself access to the technology from Xerox by giving the company Apple stock (over the strenuous objections of some of the PARC staff). Some would argue this was a "steal", but in software you really have to use that term with irony quotes. Ideas are a dime a dozen; its implementation that counts, and Apple knew how to implement it for home users where Xerox was simply incapable of that. Even Apple had to weather one commercially-failed implementation (the Lisa), before their Macintosh took off.

After the Mac came out, the power of the GUI idea was pretty obvious to everyone. Within a year Commodore and the IBM platform, and a year later Atari all had computers with GUI Operating Systems. So technically there was really nothing unique about what Microsoft did, other than perhaps the scale.

However, Apple did have cause to feel extra sore with Microsoft, as they let the company in on the concept early as part of a deal to provide software for the Mac's release. This culminated in a famous operating system "look and feel" copyright lawsuit, which Apple (quite rightly) lost².

^{1 - The word "PARC" has nearly mystical significance to those of us who were computing enthusiasts at the time, like you are talking about Bethlehem or Medina to a religious person.}

^{2 - Xerox proceeded to sue Apple for the same thing, on the reasonable theory that if copying such a thing was actually actionable, then they were the actual aggrieved party.}