I don't see how that kind of SPA is any different than a heavy pro app. Those apps often come up with their own UI scheme that people either love or hate (and usually completely ignores system preferences). A few common examples (I specifically chose Apple to illustrate) are Aperture, Logic Pro, Final Cut Pro.
You're already buying into the whole app and there's good reason to not like the design decisions they made. I also think many companies overvalue the need for it.
That's completely irrelevant. I can't imagine how ugly Blender or Photoshop's UI would become if they used my stock system scrollbars. What you're arguing over is merely a matter of preference. Some people can do it right, and pointing at the wrong examples is pointless.
But that's my point. It has a place in a very, very narrow number of applications. For those it's an all-in decision where the UI significantly changes and it's ignoring your operating system.
Photoshop for most of its history used the OS' UI paradigms. Only in the past decade or so has it adopted its own. I'm pretty sure it used the OS' scroll bars at least until CS5 around 2010.
Are you suggesting you would rather these UIs devote an unknown amount of screen real estate to various bulky OS scrollbars? That makes concise and predictable design for complex applications very difficult.
This "very, very narrow" number of applications you are suggesting is exactly what I was talking about. Those are the ones who need custom scrollbar solutions, and the way to get that done now is obtuse, brittle and hard to maintain.
> Are you suggesting you would rather these UIs devote an unknown amount of screen real estate to various bulky OS scrollbars? That makes concise and predictable design for complex applications very difficult.
In all likelihood, I probably would. I chose my OS and one reason was those conventions. Especially on the web, developers seem to make very poor decisions on when to override things like scrolling. It's reasonable if, like you said, the UI is very complex and if I'm going to spend hours using it. In practice, they mess up conventions on a single scrolling page I'm spending 2 minutes on and it's usually a clue to avoid that site in the future.
> Those are the ones who need custom scrollbar solutions, and the way to get that done now is obtuse, brittle and hard to maintain.
That /has/ to be expected if you're stomping on the conventions. If you're changing the scrollbar, you're likely significantly changing the whole UI.
> It's reasonable if, like you said, the UI is very complex and if I'm going to spend hours using it. In practice, they mess up conventions on a single scrolling page I'm spending 2 minutes on and it's usually a clue to avoid that site in the future.
Scrolljacking and replacing the scrollbar are two very different things. And the problem is that there isn't a streamlined, consistent way to replace the scrollbar, so it's always a hacky mess.
You're already buying into the whole app and there's good reason to not like the design decisions they made. I also think many companies overvalue the need for it.