I really liked XP (and 7) because for me, having a capable theming engine built in that didn't take a ton of extra resources or cause instability (unlike Stardock's WindowBlinds) was a real value add. There were some absolutely gorgeous third party XP/Vista/7 themes on sites like DeviantArt that worked extremely well within the limits of the engine, had a unique look and feel, and were just as usable as the "classic" theme.
When MS gutted the theming engine with the release of Windows 8 (flat rectangles only) I was devastated.
Absolutely. I always hated the inverse color scheme that Windows defaulted to, but that was OK because Windows had its color-scheme editor that let anyone create a global scheme he liked. I created a charcoal-toned one that was right in line with today's "dark" themes, and used it throughout the '90s.
Then Microsoft buried and ultimately removed the color-scheme editor... just in time for people to realize that inverse schemes suck.
So now Microsoft and Apple have dribbled out hard-coded "dark" themes, which every application developer has had to cobble together support for separately. Windows had this problem solved more than 30 years ago. Think about it. But then they deleted the solution from their product.
At least Apple NEVER had a proper global color palette for its UI. The fact that Microsoft did, but shitcanned it, stands testament to its complete abandonment of anything resembling good design. Hell, you can't even select multiple PNGs in Explorer and say "Open with..." anymore. The option is just totally GONE. Windows is rife with regressions like this. It's unbelievable.
Design is getting shittier and more ignorant daily. It's depressing.
The engine itself isn’t gutted - it’s full of functionality that was never lost. MS just (correctly) reasoned that transparency effects in the UI - introduced in Vista simply to show-off the capabilities of the DWM compositor - ultimately detract from a good UI.
From what I remember it lost the ability to render rounded window corners, because while Windows 8 msstyle themes existed they all had the hideous boxed corners that clashed hard with many looks.
I don’t agree that transparency is always a detractor. Judicious use can be a net positive, but it doesn’t work for all themes and there should be an option to turn it off. Personally I didn’t find the W7 variation of Aero to be bad at all.
> From what I remember it lost the ability to render rounded window corners,
...I'm guessing you haven't used Windows 11?
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By "rounded corners" are you referring to rounded-off corners in the nonclient area (such that the hWnd's rect is not clipped at all)? If so, then no: those would be rendered using a 9-grid[1] and have always been supported.
If you're referring to how so many fan/community-made msstyles for Windows 10 retain the sharp corners, I understand that's not a limitation of DWM or msstyles, just more that you need to do a lot of legwork when defining nontrivial corners in an msstyles theme; it can be done (there are plenty of examples online, e.g. look for Windows XP's style ported to Windows 10), it's just that most people don't go that far.
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[1] In msstyles, the 9-grid defines how a rectangular bitmap is stretched/scaled/tiled to fill a larger area; it's very similar to how CSS image borders are defined with `border-image-slice`.
I’m speaking specially about Windows 8/8.1. Obviously 11 and the new Fluent design language it brought don’t suffer the same issue.
Whatever the case, rounded corners on the titlebars and window chrome were common in XP/Vista/7 custom msstyles but were nowhere to be seen for 8/8.1 custom msstyles. It was one of the most frustrating aspects of that era of Windows for me.
When MS gutted the theming engine with the release of Windows 8 (flat rectangles only) I was devastated.