Question: Are there plans to separate Visual Styles from the OS?

[mdtauk]

As WinForms becomes more and more open, is there scope or plans to lift the Visual Style system (UXTheme) out of the OS, so the visual look of controls can be updated without an OS update, and be kept in sync with future UI changes in other Windows frameworks like WPF and WinUI?

[RussKie]

It is certainly something we could entertain going forward.
It is unlikely however to be implemented by us in the near-to-medium term future, but we would certainly support development proposals and contributions from the community.

/cc: @OliaG @merriemcgaw

[mdtauk]

I am not qualified enough to detail precisely how to achieve it at a technical level.

From my understanding of it, the Visual Style assets are split between a couple of files in the Windows folders, Aero.msstyle shellstyle.dll

But many apps bundle icons within their own resources, such as explorer.exe. These are outside of the scope of course.

If it were possible to fork these from the OS and create a Windows Store package with them, maintained by the Winforms team. This can be installed and winforms apps built with a certain SDK version onward, would use these versions of the visual style.

On another level, it could be made possible for developers to bundle their own visual style assets, which could override the framework or OS default ones, but this would likely require a rethink of how UXTheme works, and for it to become part of the repo.

[weltkante]

If it were possible to fork these from the OS and create a Windows Store package with them, maintained by the Winforms team.

OS theming is not implemented in .NET so transition from OS to WinForms includes rewriting it (or adding a native package to a managed project)

On another level, it could be made possible for developers to bundle their own visual style assets, which could override the framework or OS default ones

As far as I know the OS theming engine is not extensible, it is a hardcoded mix between assets, configuration files and native rendering code (but I may be mistaken, its closed source)

we would certainly support development proposals and contributions from the community.

The very core design of WinForms is to be a wrapper around native OS controls, it doesn't want to provide its own rendering/theming. I think this is a technological dead end, unless the native controls or theming engine were to be open sourced there is no community contribution possible for modernizing the visual style on a grand scale.

(I acknowledge that a mediocre middle road is possible by reimplementing rendering of native controls inside WinForms while leaving all the other events intact. This can probably be done by the community, but in my experience it tends to be very fragile to reimplement just parts of native controls without having access to their source, they used to get repainted from arbitrary event handlers without going through the official paint event. So at the end the native visual style can momentarily flicker up during certain state changes. Most observable if you ever tried to reimplement the frame drawing of a form itself, but other controls had similar issues when I last tried this.)

[mdtauk]

The very core design of WinForms is to be a wrapper around native OS controls, it doesn't want to provide its own rendering/theming. I think this is a technological dead end, unless the native controls or theming engine were to be open sourced there is no community contribution possible for modernizing the visual style on a grand scale.

This is kind of what I am thinking. If we are moving to a future where WPF, WinForms, and WinUI are open source, and the suggested ways to develop apps for Windows. There could be a time where these become the ONLY supported ways to make apps.

The other two frameworks provide their own control templates, so if the Windows team were to rework UX Theme for 20H1 onwards, it would allow for this in the future.

[merriemcgaw]

/cc: @OliaG

[stevenbrix]

WinUI is the native OS controls for Windows10. Is there a chance you could work with WinUI to layer WinForms on top of WinUI?

[RussKie]

Windows Forms is based on Win32, which isn't what WinUI is (directly) based off. Project Reunion is what supposed to bridge these two, but it is yet to be seen how this will play out.
This is not on our immediate roadmap either.