They already do, though. The big UI refresh in Win10 is all XAML, and the new Win11 taskbar (the one we all hate) is now a totally normal XAML app.
WinUI 3's big changes (to get a 3.0 version number) is not with the XAML stack itself, but its new ability to be called by unmanaged apps as a normal UI toolkit, so it can finally be used by all apps. No more using Shell UI like we're writing Win 3.1 apps.
And yes, some stuff in Win11 still isn't WinUI, which is kind of annoying, but some of those dialogs hidden away in Windows are at least 20 years old, and probably would need to be entirely rewritten, not merely have their UI's updated.
Also, fun fact: The Win8/10 taskbar's code predates Avalon (the prototype/codename for WPF), and trying to change/fix it at all usually ended up breaking it. It's one of the few binaries on Windows that would not be recompiled to build a new release image in fear of breaking it. Rewriting the taskbar made sense, GETTING RID OF SMALL MODE DID NOT, GODDAMNIT MICROSOFT.
Lets not forget that after five years Project Reunion was announced, WinUI 3.0 is yet to achieve feature parity with the Visual Studio experience developing C# or C++ applications, or UWP components features.
The WinUI map component is a Webview2 instead of proper native component, Win2D is only a subset of the UWP one, ink is yet to be migrated, and lots of other issues.
Github repos are filled with thousands of issues, and they already did a cleanup a year ago where they simply closed enough tickets to bring it under 2000.
> The Win8/10 taskbar's code predates Avalon (the prototype/codename for WPF), and trying to change/fix it at all usually ended up breaking it. It's one of the few binaries on Windows that would not be recompiled to build a new release image in fear of breaking it.
The taskbar that underwent a major redesign in Windows 7 (released after WPF)? Also, that binary is explorer.exe, surely it got rebuilt quite often for new ads. features, and fixes?
The taskbar exists in its own timeline, apparently. (Ex-)Microsoft engineers working in the UI/UX team for Windows itself have spoken about how much of a nightmare dealing with that thing was.
Also, the taskbar technically exists as a dll, not an exe, explorer.exe would link to it and run it if it was being ran as the UI shell. This is now split out to its own exe (Shell Experience Host iirc), and explorer.exe is now only File Explorer.
Since it exists as a dll, btw, this is how the Win10 taskbar injectors work, they just call the dll (which still ships in Win11) instead of letting Shell Experience Host do the Win11 thing.
The sane way of handling this, btw, is just use Shell Experience Host injectors to get the desired behaviors, such as using Windhawk and use m417z's taskbar height and icon size plugin (the third most popular Windhawk plugin); to match Vista/7 era small, set to height 32, icon size 16, taskbar button width 28.
The detail missing is that those DLLs are COM servers, so it isn't really doing injection rather the standard COM RPC.
> And yes, some stuff in Win11 still isn't WinUI, which is kind of annoying, but some of those dialogs hidden away in Windows are at least 20 years old, and probably would need to be entirely rewritten, not merely have their UI's updated.
And this is hard to do. These dialogs often are _dynamic_, with third-party settings rendered as ActiveX controls.
Thanks for the informative comment.
> small mode
I recently noticed that they introduced an option for small icons. Not that it changes much, as the height of the bar stays the same, but hey. Personally I've been fine since they added back the option not to combine buttons unless full.