[API Suggestion] Introduce Dark Mode for Apps targeting .NET 9 and Win 11

[KlausLoeffelmann]

Rationale

With a few new APIs which the Windows Team now made publicly available, we can start to introduce DarkMode functionality for WinForms. This is one of our most requested customer features. By introducing CsWin32 to our WinForms repo, adapting more and more Windows DarkMode Features overtime to WinForms is also comparatively easy to achieve.

What this feature is and is not

We have no intention to introduce full-blown theming support in WinForms with this. We want to be very mindful with this topic, since there are a lot of theming standards already out there. The API is meant as an opt in: You can use it, but if you do not, nothing should break. Existing theming concepts should continue to work as they are.

We feel though, that not only Dark Mode in particular is one of the most requested features, but it can also impose a real accessibility challenge for people - all the more, when users with visual impairments or on the neuro-diversity spectrum need to deal for example with a 80% dark and 20% bright control (like control's content dark, scrollbars light). We know, we cannot address every control, since some of them are not really themeble, but we want to standardize with this what we can, to honor those requirements as best as possible, und make sure a control can be completely dark themed (or not at all).

This PR will not go in the direction of a complete color theming feature.

General approach for applying Dark Mode

For now, you'd just use...

Later I guess we should have an additional project setting, so that also the Designer could pick up that color scheme, and then we generate and inject via ApplicationConfiguration.Initialize(). If you pick Inherits, then the System setting is applied wherever possible. (Problems are TabControl - not natively themable at all, and neither are MonthCalendar and therefore DateTimePicker). Inherits here is a "logical ambient" property, means, the idea is, that any control with that setting looks at its parent, a top-level control without a parent would look at Application.DefaultDarkMode and the Application using Inherits would look at the System.

So, for styling individual (custom) controls: If it's more than ForeColor and BackColor (and since I am working with Git Extensions, I know there is quite some coloring going on), the principal approach would be:

1. Test, if dark mode is in the current context available by using [Contropl.]IsDarkModeEnabled.
2. Access the Dark Mode/Current palette for the entire application, by using Application.SystemColors.[SystemColorName].
3. Get the color from there and style the control with it. This way, the color assignment should then work both for dark- and light mode, since that palette reflects the current setting (and we also have then a hook for future extensions).

Versioning Visual Styles for current and future A11Y requirements

Visual Styles Mode for versioning how controls render in different versions of the Framework is essential to ensure backward compatibility. This is especially important when new accessibility laws require changes in the UI, such as increasing the minimum size, padding, or margins of controls. In some cases, these adjustments can break the pixel-perfect layout of Forms or UserControls. Additionally, controls derived from a base control that changes how it requests space can potentially break other derived controls. Here are a few scenarios where versioning visual styles is required:

• New Accessibility Laws: To comply with new accessibility standards, controls may need to have larger minimum sizes, padding, or margins. For example, adjusting the padding of a TextBoxBase derived control might not be feasible without breaking existing layouts.

• Dark Mode: Dark Mode can introduce contrast issues with closely positioned controls, especially when they have non-controllable border sizes or padding. Ensuring proper spacing and rendering adjustments in Dark Mode is crucial.

• High-DPI Modes: Controls with borders defined by fixed pixel widths rather than DPI-scaled thicknesses can lead to scaling issues. Adjustments may be needed to ensure these controls render correctly in high-DPI environments.

The APIs are added to Application and Control classes, incorporating "VisualStyles" in their names to handle these scenarios. This ensures that both new and existing applications can benefit from enhanced rendering while maintaining compatibility with previous versions of the Framework.

Form (Window) Title Bar control

There will be new APIs to allow customization of the Form's title bar, including setting colors for the window border, caption, and caption text. This is based on new official public Win32 APIs, ensuring consistent and customizable window theming across different applications.

SetWindowBorderColor

Sets the color of the window border.

System.Windows.Forms.Form.SetWindowBorderColor(System.Drawing.Color color) -> void

Explanation: This method sets the color of the window border. It uses the DWM API DwmSetWindowAttribute with the DWMWA_BORDER_COLOR attribute to change the border color of the window. This is useful for customizing the appearance of the window to match the application's theme or branding.

SetWindowCaptionColor

Sets the color of the window caption (title bar).

System.Windows.Forms.Form.SetWindowCaptionColor(System.Drawing.Color color) -> void

Explanation: This method sets the color of the window caption, which is the title bar area. It leverages the DWM API DwmSetWindowAttribute with the DWMWA_CAPTION_COLOR attribute to change the title bar color. This can help make the title bar consistent with the application's dark mode or other color schemes.

SetWindowCaptionTextColor

Sets the color of the text in the window caption (title bar).

System.Windows.Forms.Form.SetWindowCaptionTextColor(System.Drawing.Color color) -> void

Explanation: This method sets the color of the text displayed in the window caption. It uses the DWM API DwmSetWindowAttribute with the DWMWA_TEXT_COLOR attribute to change the color of the title bar text, ensuring that the text remains readable and aesthetically pleasing in different modes, such as dark mode.

SetWindowCornerPreference

Sets the preference for window corner rounding.

System.Windows.Forms.Form.SetWindowCornerPreference(System.Windows.Forms.Form.WindowCornerPreference cornerPreference) -> void

Explanation: This method sets the preference for window corner rounding. It uses the DWM API DwmSetWindowAttribute with the DWMWA_WINDOW_CORNER_PREFERENCE attribute to specify how the window corners should be rendered (rounded or not). The possible values are:

System.Windows.Forms.Form.WindowCornerPreference.Default = 0 -> System.Windows.Forms.Form.WindowCornerPreference
System.Windows.Forms.Form.WindowCornerPreference.DoNotRound = 1 -> System.Windows.Forms.Form.WindowCornerPreference
System.Windows.Forms.Form.WindowCornerPreference.Round = 2 -> System.Windows.Forms.Form.WindowCornerPreference
System.Windows.Forms.Form.WindowCornerPreference.RoundSmall = 3 -> System.Windows.Forms.Form.WindowCornerPreference

Current Progress and Problematic Areas

One thing which is already be important to know (and to have in the docs later, should we get this feature in for .NET 9): We will most likely not achieve dark mode for all controls from the get-go (probably even for some of them ever). Problematic controls maybe MonthCalendar, DateTimePicker and definitely TabControl at this point. There are workarounds, I guess, but they are a bit awkward. @adegeo: I want to ping you for this as early as possible, so you're know about this (literal) development from day 1.

• [x] New API for DarkMode control on Application.
• [x] New API for DarkMode control on Control.
• [x] Mapping SystemColors -> Application.SystemColors/patch for DarkMode
• [x] New API for controlling Form Titelbar Color/BorderColor/TextColor
• [x] Scrollbars for Form/ScrollableControl/ListView/TreeView/ListBox/ComboBox
• [x] Radio Button
• [x] CheckBox
• [x] ComboBox DarkMode
• [x] Button DarkMode
• [x] TreeView DarkMode
• [x] ListView DarkMode
• [x] TextBox/RichtextBox
• [x] Strips - Still have issues, but the basics work fine!
• [x] Groupbox Caption
• [x] ColumnHeaders ListView Forground Text
• [x] ListView Forground Group Caption (might be an issue to get it brighter).
• [ ] DataGridView (Content renders correctly, Headers/Styles need more work)
• [ ] !!! TabControl (Scrollbars are working in DarkMode alright, but theming this thing would be a very improvised construct. If someone has a good idea or approach, have at it!)
• [ ] !!! MonthCalendar (Honestly: We should have a new one altogether - that thing is a visual and A11Y NIGHTMARE.)
• [ ] !!!DateTimePicker - uses MonthCalendar, so go figure.

*************************************************************
Please take the branch, compile and help testing! :-)
*************************************************************

Current list of new APIs

[Subject to change at this point!]

// ***************************************
// Dark Mode Control
// ***************************************

static System.Windows.Forms.Application.DefaultDarkMode.get -> System.Windows.Forms.DarkMode
static System.Windows.Forms.Application.EnvironmentDarkMode.get -> System.Windows.Forms.DarkMode
static System.Windows.Forms.Application.IsDarkModeEnabled.get -> bool
static System.Windows.Forms.Application.SetDefaultDarkMode(System.Windows.Forms.DarkMode darkMode) -> bool
System.Windows.Forms.Control.DarkMode.get -> System.Windows.Forms.DarkMode
System.Windows.Forms.Control.DarkMode.set -> void
System.Windows.Forms.DarkMode
System.Windows.Forms.DarkMode.Disabled = 3 -> System.Windows.Forms.DarkMode
System.Windows.Forms.DarkMode.Enabled = 2 -> System.Windows.Forms.DarkMode
System.Windows.Forms.DarkMode.Inherits = 1 -> System.Windows.Forms.DarkMode
System.Windows.Forms.DarkMode.NotSupported = 0 -> System.Windows.Forms.DarkMode
virtual System.Windows.Forms.Control.DarkModeSupported.get -> bool
virtual System.Windows.Forms.Control.DefaultVisualStylesMode.get -> System.Windows.Forms.VisualStylesMode
virtual System.Windows.Forms.Control.IsDarkModeEnabled.get -> bool
virtual System.Windows.Forms.Control.SetDarkModeCore(System.Windows.Forms.DarkMode darkModeSetting) -> bool

// ***************************************
// Visual Styles Versioning
// ***************************************

System.Windows.Forms.VisualStylesMode
System.Windows.Forms.VisualStylesMode.Disabled = 0 -> System.Windows.Forms.VisualStylesMode
System.Windows.Forms.VisualStylesMode.Latest = 32767 -> System.Windows.Forms.VisualStylesMode
System.Windows.Forms.VisualStylesMode.Legacy = 8 -> System.Windows.Forms.VisualStylesMode
System.Windows.Forms.VisualStylesMode.Version10 = 10 -> System.Windows.Forms.VisualStylesMode
System.Windows.Forms.Control.VisualStylesMode.get -> System.Windows.Forms.VisualStylesMode
System.Windows.Forms.Control.VisualStylesMode.set -> void
static System.Windows.Forms.Application.DefaultVisualStylesMode.get -> System.Windows.Forms.VisualStylesMode
static System.Windows.Forms.Application.IsVisualStylesSupported.get -> bool
static System.Windows.Forms.Application.SetDefaultVisualStylesMode(System.Windows.Forms.VisualStylesMode styleSetting) -> void

override System.Windows.Forms.MaskedTextBox.DefaultVisualStylesMode.get -> System.Windows.Forms.VisualStylesMode
override System.Windows.Forms.RichTextBox.DefaultVisualStylesMode.get -> System.Windows.Forms.VisualStylesMode
override System.Windows.Forms.TextBox.DefaultVisualStylesMode.get -> System.Windows.Forms.VisualStylesMode

[Obsolete?]
virtual System.Windows.Forms.Control.ValidateVisualStylesMode(System.Windows.Forms.VisualStylesMode visualStylesMode) -> bool

// ***************************************
// Windows Title Bar Control (based on new official public Win32 APIs)
// ***************************************

System.Windows.Forms.Form.SetWindowBorderColor(System.Drawing.Color color) -> void
System.Windows.Forms.Form.SetWindowCaptionColor(System.Drawing.Color color) -> void
System.Windows.Forms.Form.SetWindowCaptionTextColor(System.Drawing.Color color) -> void
System.Windows.Forms.Form.SetWindowCornerPreference(System.Windows.Forms.Form.WindowCornerPreference cornerPreference) -> void
System.Windows.Forms.Form.WindowCornerPreference
System.Windows.Forms.Form.WindowCornerPreference.Default = 0 -> System.Windows.Forms.Form.WindowCornerPreference
System.Windows.Forms.Form.WindowCornerPreference.DoNotRound = 1 -> System.Windows.Forms.Form.WindowCornerPreference
System.Windows.Forms.Form.WindowCornerPreference.Round = 2 -> System.Windows.Forms.Form.WindowCornerPreference
System.Windows.Forms.Form.WindowCornerPreference.RoundSmall = 3 -> System.Windows.Forms.Form.WindowCornerPreference

// ***************************************
// DarkMode Color Scheming. These are public but read only. We do not support full theming.
// ***************************************

System.Windows.Forms.ApplicationColors
System.Windows.Forms.ApplicationColors.ApplicationColors() -> void
static System.Windows.Forms.Application.ApplicationColors.get -> System.Windows.Forms.ApplicationColors!
virtual System.Windows.Forms.ApplicationColors.ActiveBorder.get -> System.Drawing.Color
virtual System.Windows.Forms.ApplicationColors.ActiveCaption.get -> System.Drawing.Color
virtual System.Windows.Forms.ApplicationColors.ActiveCaptionText.get -> System.Drawing.Color
virtual System.Windows.Forms.ApplicationColors.AppWorkspace.get -> System.Drawing.Color
virtual System.Windows.Forms.ApplicationColors.ButtonFace.get -> System.Drawing.Color
virtual System.Windows.Forms.ApplicationColors.ButtonHighlight.get -> System.Drawing.Color
virtual System.Windows.Forms.ApplicationColors.ButtonShadow.get -> System.Drawing.Color
virtual System.Windows.Forms.ApplicationColors.Control.get -> System.Drawing.Color
virtual System.Windows.Forms.ApplicationColors.ControlDark.get -> System.Drawing.Color
virtual System.Windows.Forms.ApplicationColors.ControlDarkDark.get -> System.Drawing.Color
virtual System.Windows.Forms.ApplicationColors.ControlLight.get -> System.Drawing.Color
virtual System.Windows.Forms.ApplicationColors.ControlLightLight.get -> System.Drawing.Color
virtual System.Windows.Forms.ApplicationColors.ControlText.get -> System.Drawing.Color
virtual System.Windows.Forms.ApplicationColors.Desktop.get -> System.Drawing.Color
virtual System.Windows.Forms.ApplicationColors.GradientActiveCaption.get -> System.Drawing.Color
virtual System.Windows.Forms.ApplicationColors.GradientInactiveCaption.get -> System.Drawing.Color
virtual System.Windows.Forms.ApplicationColors.GrayText.get -> System.Drawing.Color
virtual System.Windows.Forms.ApplicationColors.Highlight.get -> System.Drawing.Color
virtual System.Windows.Forms.ApplicationColors.HighlightText.get -> System.Drawing.Color
virtual System.Windows.Forms.ApplicationColors.HotTrack.get -> System.Drawing.Color
virtual System.Windows.Forms.ApplicationColors.InactiveBorder.get -> System.Drawing.Color
virtual System.Windows.Forms.ApplicationColors.InactiveCaption.get -> System.Drawing.Color
virtual System.Windows.Forms.ApplicationColors.InactiveCaptionText.get -> System.Drawing.Color
virtual System.Windows.Forms.ApplicationColors.Info.get -> System.Drawing.Color
virtual System.Windows.Forms.ApplicationColors.InfoText.get -> System.Drawing.Color
virtual System.Windows.Forms.ApplicationColors.Menu.get -> System.Drawing.Color
virtual System.Windows.Forms.ApplicationColors.MenuBar.get -> System.Drawing.Color
virtual System.Windows.Forms.ApplicationColors.MenuHighlight.get -> System.Drawing.Color
virtual System.Windows.Forms.ApplicationColors.MenuText.get -> System.Drawing.Color
virtual System.Windows.Forms.ApplicationColors.ScrollBar.get -> System.Drawing.Color
virtual System.Windows.Forms.ApplicationColors.Window.get -> System.Drawing.Color
virtual System.Windows.Forms.ApplicationColors.WindowFrame.get -> System.Drawing.Color
virtual System.Windows.Forms.ApplicationColors.WindowText.get -> System.Drawing.Color

[RussKie]

I suggest avoiding "dark" in the API names. At some point in time Windows could introduce a new mode - say, blue - and that wouldn't fit into the proposed API.

Historically, the colours were part of the theme definition, now it appears Windows is making a distinction between "colours" and "themes" - the former is the selection of "light" vs "dark", and the latter is now accessibility related:

I think IsDarkModeEnabled should be a part of Application type - as this setting affects the application as a whole. As per the discussion with the Windows team, the only option for the Win32 app to find out the current configuration is vie the registry:

Computer\HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Themes\Personalize
• SystemUsesLightTheme=0|1
• AppsUseLightTheme=0|1

NB: we still need to confirm this has been officially documented.

[KlausLoeffelmann]

I suggest avoiding "dark" in the API names. At some point in time Windows could introduce a new mode - say, blue - and that wouldn't fit into the proposed API.

I thought about that for a while. I decided to use Dark Mode in the name, because I followed the public Windows API, which the prototype is based on, and which does the same. Another point is that Dark Mode is meanwhile a buzz word, so I'd argue it helps with discoverability. Therefore, I strongly advocate to continue using Dark Mode.

I think IsDarkModeEnabled should be a part of Application type - as this setting affects the application as a whole.

This is what Application.EnvironmentDarkMode does. It returns either Enabled or Disabled ... or ... NotSupported. And this is why a boolean value does not suffice. You want not only to know, if it's on or off, you also want to know, if it's available altogether on that particular machine/platform.

As per the discussion with the Windows team, the only option for the Win32 app to find out the current configuration is ...

Yes. That's how I implemented the prototype already. There is another way which we already know is supported, but that one does use WinRT projected API, and I want to talk with @JeremyKuhne first, if that is an option for us. Also, that way to achieve it seems a bit stilted, but I am still investigating this, so, we'll see what route will be best.

[paul1956]

How is the prototype/feature going to be exposed? Does it depend on specific version of Windows 7/10/11/next...? Do Control vendors custom controls need to support this?

[kirsan31]

Guys I am sorry, but when it comes to themes / modes - https://github.com/dotnet/winforms/issues/3691 immediately rings in my head (and I can't get away from it) 🙄

[KlausLoeffelmann]

Sadly true. I am only very carefully optimistic that Windows will change anything in that regard. And I know custom NC-Painting is probably not an option. @RussKie, didn't you have something here?

[DualBrain]

Yep... yep... yep... yep... and yep!

[RussKie]

didn't you have something here?

Yes, I tinkered with NC- and C-painting of the form in the VS designer context. I got some partial progress, but that'd require more time (which is a bit scarce). Custom rendering of MDI windows could be a significant challenge.

[kirsan31]

Yes, I tinkered with NC- and C-painting of the form in the VS designer context. I got some partial progress, but that'd require more time (which is a bit scarce). Custom rendering of MDI windows could be a significant challenge.

Is the Windows team so untouchable? 😕

[paul1956]

Are MDI windows used that much that a 99% solution isn't worth releasing as a start?

[KlausLoeffelmann]

The issue here also is that MDI-Windows aren't really the best idea for user interfaces, and so neither Windows nor we recommend these. We have no plans to really obsolete them alright, but they aren't really a good idea. That said, the rendering of MDI Windows is one thing. But in WinForms, you can also host a Form as a control in another Form. That then isn't technically an MDI window, although the same (rendering) principle applies. Which leads to the outdated look and feel, that cannot be changed easily (so, also the same applies as for MDI windows). Our own Designer is bitten by that: The reason the Designer Form adornments are looking outdated is the reason for that, so there is some internal motivation to change that. But at the same time, you don't really do much with the (NC) window controls of the Form in the Designer in this case. Actually nothing: The adornments of the Form in the Designer are just supposed to look pretty. Nothing else. The window never really moves inside its container, you can only resize it. With MDI windows that's quite different: And I am afraid, that NC painting will just get its own "dynamics" at one point and opens all other sorts of problems in the Real world. That's why I am personally really hesitant to address the Windows-inside-Windows-look-outdated issue with custom NC painting in the runtime and per se.

@DualBrain: Do you have any experiences here in that regard?

[kirsan31]

@KlausLoeffelmann

The issue here also is that MDI-Windows aren't really the best idea for user interfaces, and so neither Windows nor we recommend these. We have no plans to really obsolete them alright, but they aren't really a good idea.

Can I ask - why (except https://github.com/dotnet/winforms/issues/3691 of course 😁 )? I often hear a similar statement but without any arguments 🤷‍♂️ But I have arguments in defense of MDI:

1. MDI is the only multi windows layout that WinForms can offer you out of the box.
2. This is the most stable (error free) noncommercial multi windows layout for WinForms.
3. So far great if you need to manage multiple windows that are visible at the same time and can be quickly minimized/restored. I mean for such tasks MDI still better fit then V.S. dock layout...
4. About obsoleting MDI... Pls look at WinForms repo issues sorted by 👍: I think if you say that MDI is outdated and not worth fixing / maintaining, then all this can be safely projected onto the entire WinForms 😥

[DualBrain]

But in WinForms, you can also host a Form as a control in another Form.

I will confirm that I do (regularly) utilize this technique and can share that it does present some challenges - with that said, sometimes these challenges are less of an issue than attempting alternative methods (code rewrite, inheritance, etc.); a real pros vs. cons situation where accepting the challenges/limitations of embedding a window within a window.

Now with that said, when I do this it is typically done in a way where the embedded window is treated more like a control rather than something that will move about within the confines of the containing window.

[DualBrain]

I do tend to agree that MDI (in its current form) is a bit dated; however, there many scenarios where this approach is still very valid. While I don't personally design projects around this model, I do stumble across projects every once and a while that do; as such, I don't see MDI going away any time soon - at least not without a very solid/clear replacement available.

In order to handle "dark mode", what I've currently been doing is pretty much working within the very limited feature set that can do it and trying to design my applications to work within these limitations.

Honestly, I really didn't even realize how limited this really was until I attempted to get @paul1956's project switched over... meaning trying to apply dark mode to an already existing project changing the overall design/layout/interface really isn't that much of an option.

Some components are simply "too difficult" to repaint without effectively replacing them because they don't expose any functionality to affect any sort of color changes (comboboxes) while others are what I would refer to as being 90-95% there, but that last little percent is very visibly annoying (toolbar/statusbar). Menus are actually pretty good.

With all that said, the first thing that is needed is exactly what the original topic of this issue raises... need some way to identify that Windows a) supports dark mode and b) is in dark mode. Sure, you can just have a mechanism in place to allow the end-user to select / switch between; but from my point of view I would like to default my application to what the user has already specified within the system.

And, assuming that is possible, have the ability to tell my application that it is in dark mode or not affecting (automagically) standard components accordingly. This does need to be something that I, as the developer, can manually toggle in a tri-state manner - auto (system setting), enabled (dark mode active), disabled (dark mode inactive).

As to whether or not MDI handles this or if MDI delays this getting done... my opinion is that this feature should be something that could be made available incrementally; meaning it needs to be totally "opt-in" allow for use to take advantage of these pieces if we are willing/able. To say this another way, I don't think dark mode capability should be an all or nothing feature... identify the main sore spots and address those incrementally. Default to application.darkmode = disabled allowing for enabled/auto.

I recognize that I'm making this sound easier than it really is; but I really don't favor the approach of waiting 3 years to get a better combobox, status bar, etc. (meaning the more common of the common controls).

As for the menu... please, please, please feel free to "borrow" from my efforts and use as you see fit. Again, I'd love to just be able to set a single property and "it just work".

[KlausLoeffelmann]

@kirsan31, @DualBrain: When it comes to MDI Windows, WinForms just follows the Windows/Office guidelines. It doesn't have to do with my/general personal preference, it's just a very functional reason: When multi-monitor display scenarios became common even in conservative work environments like Banks, Insurance Companies, Government Departments (all typical WinForms target audiences), MDI user interface just became totally unpractical: You simply can't drag a document to a secondary monitor, when you have a constraining MDI parent on the primary monitor. And with that (I say that from a very strong personal experience as a consultant in the area of migrating/modernizing Win32, VB6 and older WinForms/WPF apps in a previous life) End Users started to demand other UI paradigms.

[KlausLoeffelmann]

Still, I recognize that we need to support existing apps with that - so, no, no one said anything about obsoleting it. All that I am saying is, that it'll be very likely that we (WinForms) won't invest in a scenario, that a) doesn't make sense in modern work environments, and b) that isn't very likely supported (in terms of modernizing) by Windows. Should they decide to introduce theming, then we would very likely pick that up and enable it. But I don't think it would make sense for us (WinForms) to start messing with a NC-Custom-rendering approach.

[DualBrain]

@KlausLoeffelmann Sorry if it didn't come across properly; but I was trying to clarify that MDI is what it is, pretty much isn't (or rather shouldn't be) going anywhere and although not generally recommended, there are scenarios where it is being used and/or may be useful. As I said, I don't particularly utilize it as I would much rather have docking, tabbed, tear-away model than MDI. ;-)

Additionally, I definitely don't want MDI doing one thing or another preventing/delaying the moving forward with dark mode.

[kirsan31]

I think I've been misunderstood here. I didn't offer to slow down this work because of the MDI. I just wanted to remind that we have an unfixed bug on this topic for a very long time, and it's time to kick the Windows team harder...

@KlausLoeffelmann for not to flood, I answered in the relevant topic.

[Balkoth]

Dark mode is easily my most wanted feature for winforms. Second would be a working PMv2 mode...

[driver1998]

Is the dark common control theme documented now? Last time I checked it is still undocumented. Only the dark title bar attribute is documented and public.

[Tanya-Solyanik]

Another issue that requires UxTHeme team to open up an API for us - https://github.com/dotnet/winforms/issues/6657

[jonesy-b-dev]

Any more info if this will be implemented?

[Laim]

Before the end of the 2020’s if we’re lucky. It’s just been shifted from .NET 8 to .NET 9. Sent from my iPhoneOn 14 Nov 2023, at 11:58, Jonas de Bruin @.***> wrote: Any more info if this will be implemented?

—Reply to this email directly, view it on GitHub, or unsubscribe.You are receiving this because you are subscribed to this thread.Message ID: @.***>

[jonesy-b-dev]

Thats still really long, thought this was really high requested.

[Laim]

Thats still really long, thought this was really high requested.

Projected release date for .NET 9 is November 2024, so yeah - I don't have much hope to be honest.

[driver1998]

To do this properly, WinForms would need to have access to public Windows APIs to enable dark mode on Win32 Common Controls. There are some (see https://github.com/microsoft/WindowsAppSDK/issues/41), but these are internal use for the File Explorer dark mode effort only. I don't think WinForms would want to rely on undocumented APIs.

Also, there exists other APIs in uxtheme.dll which might be of interest for people transitioning to WinUI and/or XAML islands:

SetPreferredAppMode: This allows apps to enable dark theme support for Win32 controls. This is notably used by Windows Explorer for its dark theme. AllowDarkModeForWindow: Once the app mode is set to AllowDark using the API above, it is a per-window opt-in. Once this method is called, the Win32 controls in the window uses dark theme if the system dark theme is enabled, and automatically switches to light theme when the user changes their settings. Note that some controls might need to have their theme manually set to DarkMode_Explorer for this to be effective Dark mode ribbon can be opt-in with the window property UI_PKEY_DarkModeRibbon

WinForms supporting dark mode should be a major push of this effort to go public, since native Win32 controls is at the very core of WinForms since day 1.

[paul1956]

@driver1998 File Explorer is not going to lose Dark Mode and WinForms will expose it own public API to switch so why is it an issue to use undocumented API's that are being used elsewhere in critical functionality. In the unlikely event that the API changes WinForms can respond while in parallel work with Windows team to make API public.

[AraHaan]

Instead of relying on dark mode API's why not use SVG images that can provide the actual looks of all of the controls, then have the application developers register theme color xml files that can then be selected for use to recolor said SVG files. Also with SVG being the easiest to manipulate and render it should be a minimal change on that then without the need for any dark mode API's. Also another + is the developer could then define their own colors they want used for their application as well and it would make it look professional as well with no added complexity or work for them which would make it worth it to them. Also plus is the theme would apply globally to every form and control automatically as well.

[MagicAndre1981]

Also another + is the developer could then define their own colors they want used for their application as well

I need to do this color defining in xmls for Xamarin.Forms and hate it. I don't want to do this for Winforms, too. I would like to have something like in UWP with RequestedTheme Property which as an enum of Dark, Default, Light to request how the control are rendered.

[AraHaan]

Also another + is the developer could then define their own colors they want used for their application as well

I need to do this color defining in xmls for Xamarin.Forms and hate it. I don't want to do this for Winforms, too. I would like to have something like in UWP with RequestedTheme Property which as an enum of Dark, Default, Light to request how the control are rendered.

The color defines in that case would be for text that would be rendered on the svg images 😄. I have a good function that basically does in memory edits to svg contents before converting them in memory to a System.Drawing.Bitmap that then gets rendered on an image control to basically look and feel like a normal button 😄.

[KlausLoeffelmann]

Just as a general disclaimer:

We have no intention to introduce full-blown theming support in WinForms with this. We want to be very mindful with this topic, since there are a lot of theming standards already out there. The API is meant as an opt in: You can use it, but if you do not, nothing should break. Existing theming concepts should continue to work as they are.

We feel though, that not only Dark Mode in particular is one of the most requested features, but it can also impose a real accessibility challenge for people - all the more, when users with visual impairments or on the neuro-diversity spectrum need to deal for example with a 80% dark and 20% bright control (like control's content dark, scrollbars light). We know, we cannot address every control, since some of them are not really themeble, but we want to standardize with this what we can, to honor those requirements as best as possible, und make sure a control can be completely dark themed (or not at all).

This PR will not go in the direction of a complete color theming feature.