Dark Theme Flickering To Light Theme Randomly

VanBuren77 commented 3 weeks ago

Describe the bug

Application Dark Theme flickering to Light Theme

To Reproduce

This is very difficult to reproduce, but effectively, I start the gallery sample application and switch to dark mode. After some time, or after triggering something on another widow, the application's theme will switch back to light mode. I am unable to consistently reproduce the bug, but after clicking on the "All samples" and mousing over the "Home" navigator it occurred. However, this doesn't happen consistently. And it seems to be triggered by other various events.

Expected behavior

I expect to simply click on dark mode and have the application remain on dark mode until I click on the button that triggers the SwitchThemes function.

Screenshots

No response

OS version

Windows 10 Enterprise

.NET version

8.0

WPF-UI NuGet version

main branch under the gallery:

4.0.0-rc.2

Additional context

Unfortunately this is very difficult to reproduce! I wish I could pinpoint the cause of what causes the theme flicker. Identifying the cause will likely lead to a clear fix. I suspect this is some resource failing to load.

VanBuren77 commented 3 weeks ago

I captured some of the output below; you can see the system is attempting to set to light theme several times in a row without user input.

Microsoft.Hosting.Lifetime: Information: Application started. Press Ctrl+C to shut down. Microsoft.Hosting.Lifetime: Information: Hosting environment: Production Microsoft.Hosting.Lifetime: Information: Content root path: C:\Projects\GitHub\wpfui-main\src\Wpf.Ui.Gallery\bin\Debug\net8.0-windows10.0.22621.0 'Wpf.Ui.Gallery.exe' (CoreCLR: clrhost): Loaded 'C:\Program Files\dotnet\shared\Microsoft.NETCore.App\8.0.8\System.Runtime.Serialization.Formatters.dll'. Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled. 'Wpf.Ui.Gallery.exe' (CoreCLR: clrhost): Loaded 'C:\Program Files\dotnet\shared\Microsoft.NETCore.App\8.0.8\System.Runtime.Intrinsics.dll'. Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled. DEBUG | a7c25928204b4fe39df57c2e42555e18 - Icons - Wpf.Ui.Gallery.Views.Pages.DesignGuidance.IconsPage | NAVIGATED JOURNAL INDEX 2 JOURNAL LAST ELEMENT a7c25928204b4fe39df57c2e42555e18 Wpf.Ui.Accent: INFO | SystemAccentColor: #FF0078D7 Wpf.Ui.Accent: INFO | SystemAccentColorPrimary: #FF1E9BFD Wpf.Ui.Accent: INFO | SystemAccentColorSecondary: #FF3DA9FF Wpf.Ui.Accent: INFO | SystemAccentColorTertiary: #FF5CB7FF Wpf.Ui.Accent: INFO | Text on accent is DARK ApplicationThemeManager: INFO | Wpf.Ui.Appearance.ApplicationThemeManager tries to update theme to Dark (Dark): True Wpf.Ui.TitleBar: INFO | Wpf.Ui.Controls.TitleBar received theme - Dark 'Wpf.Ui.Gallery.exe' (CoreCLR: clrhost): Loaded 'C:\Program Files\dotnet\shared\Microsoft.NETCore.App\8.0.8\System.Diagnostics.StackTrace.dll'. Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled. DEBUG | 2b05bf46210448e7aa166f9316809265 - Colors - Wpf.Ui.Gallery.Views.Pages.DesignGuidance.ColorsPage | NAVIGATED JOURNAL INDEX 3 JOURNAL LAST ELEMENT 2b05bf46210448e7aa166f9316809265 DEBUG | 8a95bf7ad7044bb08fcf3626ccaf8db3 - All samples - Wpf.Ui.Gallery.Views.Pages.AllControlsPage | NAVIGATED JOURNAL INDEX 4 JOURNAL LAST ELEMENT 8a95bf7ad7044bb08fcf3626ccaf8db3 DEBUG | e5341f8df8ec4a7a9c6899a1e1f562c4 - Typography - Wpf.Ui.Gallery.Views.Pages.DesignGuidance.TypographyPage | NAVIGATED JOURNAL INDEX 5 JOURNAL LAST ELEMENT e5341f8df8ec4a7a9c6899a1e1f562c4 DEBUG | e24256ecb8444d3b88aaa4dd7fffcc5b - Home - Wpf.Ui.Gallery.Views.Pages.DashboardPage | NAVIGATED JOURNAL INDEX 6 JOURNAL LAST ELEMENT e24256ecb8444d3b88aaa4dd7fffcc5b The thread '[Thread Destroyed]' (39112) has exited with code 0 (0x0). The thread '[Thread Destroyed]' (10424) has exited with code 0 (0x0). The thread '[Thread Destroyed]' (32740) has exited with code 0 (0x0). The thread '[Thread Destroyed]' (37168) has exited with code 0 (0x0). The thread '[Thread Destroyed]' (40764) has exited with code 0 (0x0). DEBUG | 2b05bf46210448e7aa166f9316809265 - Colors - Wpf.Ui.Gallery.Views.Pages.DesignGuidance.ColorsPage | NAVIGATED JOURNAL INDEX 7 JOURNAL LAST ELEMENT 2b05bf46210448e7aa166f9316809265 DEBUG | 8a95bf7ad7044bb08fcf3626ccaf8db3 - All samples - Wpf.Ui.Gallery.Views.Pages.AllControlsPage | NAVIGATED JOURNAL INDEX 8 JOURNAL LAST ELEMENT 8a95bf7ad7044bb08fcf3626ccaf8db3 DEBUG | 2b05bf46210448e7aa166f9316809265 - Colors - Wpf.Ui.Gallery.Views.Pages.DesignGuidance.ColorsPage | NAVIGATED JOURNAL INDEX 9 JOURNAL LAST ELEMENT 2b05bf46210448e7aa166f9316809265 The thread '[Thread Destroyed]' (7372) has exited with code 0 (0x0). The thread '[Thread Destroyed]' (4276) has exited with code 0 (0x0). The thread '[Thread Destroyed]' (40896) has exited with code 0 (0x0). The thread '[Thread Destroyed]' (32836) has exited with code 0 (0x0). The thread '[Thread Destroyed]' (38856) has exited with code 0 (0x0). The thread '[Thread Destroyed]' (9060) has exited with code 0 (0x0). The thread '[Thread Destroyed]' (23108) has exited with code 0 (0x0). The thread '[Thread Destroyed]' (26744) has exited with code 0 (0x0). The thread '[Thread Destroyed]' (33772) has exited with code 0 (0x0). The thread '[Thread Destroyed]' (40704) has exited with code 0 (0x0). The thread '[Thread Destroyed]' (40928) has exited with code 0 (0x0). The thread '[Thread Destroyed]' (43996) has exited with code 0 (0x0). The thread '[Thread Destroyed]' (18456) has exited with code 0 (0x0). The thread '[Thread Destroyed]' (43268) has exited with code 0 (0x0). The thread '[Thread Destroyed]' (38044) has exited with code 0 (0x0). The thread '[Thread Destroyed]' (37224) has exited with code 0 (0x0). The thread '[Thread Destroyed]' (35520) has exited with code 0 (0x0). The thread '[Thread Destroyed]' (35956) has exited with code 0 (0x0). The thread '[Thread Destroyed]' (36692) has exited with code 0 (0x0). The thread '[Thread Destroyed]' (38072) has exited with code 0 (0x0). The thread '[Thread Destroyed]' (38292) has exited with code 0 (0x0). The thread '[Thread Destroyed]' (10256) has exited with code 0 (0x0). Wpf.Ui.Accent: INFO | SystemAccentColor: #FF0078D7 Wpf.Ui.Accent: INFO | SystemAccentColorPrimary: #FF0071CA Wpf.Ui.Accent: INFO | SystemAccentColorSecondary: #FF006ABE Wpf.Ui.Accent: INFO | SystemAccentColorTertiary: #FF0063B1 Wpf.Ui.Accent: INFO | Text on accent is LIGHT ApplicationThemeManager: INFO | Wpf.Ui.Appearance.ApplicationThemeManager tries to update theme to Light (Light): True Wpf.Ui.TitleBar: INFO | Wpf.Ui.Controls.TitleBar received theme - Light SystemThemeWatcher: INFO | 72044 (WPF UI Gallery) triggered the application theme change to Light. Wpf.Ui.Accent: INFO | SystemAccentColor: #FF0078D7 Wpf.Ui.Accent: INFO | SystemAccentColorPrimary: #FF0071CA Wpf.Ui.Accent: INFO | SystemAccentColorSecondary: #FF006ABE Wpf.Ui.Accent: INFO | SystemAccentColorTertiary: #FF0063B1 Wpf.Ui.Accent: INFO | Text on accent is LIGHT ApplicationThemeManager: INFO | Wpf.Ui.Appearance.ApplicationThemeManager tries to update theme to Light (Light): True Wpf.Ui.TitleBar: INFO | Wpf.Ui.Controls.TitleBar received theme - Light SystemThemeWatcher: INFO | 72044 (WPF UI Gallery) triggered the application theme change to Light. The thread '[Thread Destroyed]' (33968) has exited with code 0 (0x0). The thread '[Thread Destroyed]' (35300) has exited with code 0 (0x0). Wpf.Ui.Accent: INFO | SystemAccentColor: #FF0078D7 Wpf.Ui.Accent: INFO | SystemAccentColorPrimary: #FF0071CA Wpf.Ui.Accent: INFO | SystemAccentColorSecondary: #FF006ABE Wpf.Ui.Accent: INFO | SystemAccentColorTertiary: #FF0063B1 Wpf.Ui.Accent: INFO | Text on accent is LIGHT ApplicationThemeManager: INFO | Wpf.Ui.Appearance.ApplicationThemeManager tries to update theme to Light (Light): True Wpf.Ui.TitleBar: INFO | Wpf.Ui.Controls.TitleBar received theme - Light SystemThemeWatcher: INFO | 72044 (WPF UI Gallery) triggered the application theme change to Light. Wpf.Ui.Accent: INFO | SystemAccentColor: #FF0078D7 Wpf.Ui.Accent: INFO | SystemAccentColorPrimary: #FF0071CA Wpf.Ui.Accent: INFO | SystemAccentColorSecondary: #FF006ABE Wpf.Ui.Accent: INFO | SystemAccentColorTertiary: #FF0063B1 Wpf.Ui.Accent: INFO | Text on accent is LIGHT ApplicationThemeManager: INFO | Wpf.Ui.Appearance.ApplicationThemeManager tries to update theme to Light (Light): True Wpf.Ui.TitleBar: INFO | Wpf.Ui.Controls.TitleBar received theme - Light SystemThemeWatcher: INFO | 72044 (WPF UI Gallery) triggered the application theme change to Light. Wpf.Ui.Accent: INFO | SystemAccentColor: #FF0078D7 Wpf.Ui.Accent: INFO | SystemAccentColorPrimary: #FF0071CA Wpf.Ui.Accent: INFO | SystemAccentColorSecondary: #FF006ABE Wpf.Ui.Accent: INFO | SystemAccentColorTertiary: #FF0063B1 Wpf.Ui.Accent: INFO | Text on accent is LIGHT ApplicationThemeManager: INFO | Wpf.Ui.Appearance.ApplicationThemeManager tries to update theme to Light (Light): True Wpf.Ui.TitleBar: INFO | Wpf.Ui.Controls.TitleBar received theme - Light SystemThemeWatcher: INFO | 72044 (WPF UI Gallery) triggered the application theme change to Light. Wpf.Ui.Accent: INFO | SystemAccentColor: #FF0078D7 Wpf.Ui.Accent: INFO | SystemAccentColorPrimary: #FF0071CA Wpf.Ui.Accent: INFO | SystemAccentColorSecondary: #FF006ABE Wpf.Ui.Accent: INFO | SystemAccentColorTertiary: #FF0063B1 Wpf.Ui.Accent: INFO | Text on accent is LIGHT

VanBuren77 commented 2 weeks ago

I set a breakpoint on the OnThemeChanged under the TitleBar in Wpf.Ui./ Wpf.Ui.Controls.TitleBar

It happens in this highest part of the call stack:

/// <summary>
/// Listens to system messages on the application windows.
/// </summary>
private static IntPtr WndProc(IntPtr hWnd, int msg, IntPtr wParam, IntPtr lParam, ref bool handled)
{
    if (msg == (int)User32.WM.WININICHANGE)
    {
        UpdateObservedWindow(hWnd);
    }

    return IntPtr.Zero;
}

public static void ApplySystemTheme(bool updateAccent)
{
    SystemThemeManager.UpdateSystemThemeCache();

    SystemTheme systemTheme = GetSystemTheme();

    ApplicationTheme themeToSet = ApplicationTheme.Light;

    if (systemTheme is SystemTheme.Dark or SystemTheme.CapturedMotion or SystemTheme.Glow)
    {
        themeToSet = ApplicationTheme.Dark;
    }
    else if (
        systemTheme is SystemTheme.HC1 or SystemTheme.HC2 or SystemTheme.HCBlack or SystemTheme.HCWhite
    )
    {
        themeToSet = ApplicationTheme.HighContrast;
    }

    Apply(themeToSet, updateAccent: updateAccent);
}

I think it's auto trying to set to my system theme.

VanBuren77 commented 2 weeks ago

I realize this may be a function of wanting the SystemThemeWatcher to watch for the system theme and then update. When this isn't made clear, this appears as a theme flickering bug. I think the solution would be to; if this is enabled, prevent the ability to switch to something other than the system theme. Otherwise, this is a hidden behavior.

lepoco / wpfui