feat: support for dark app mode

Basic adaption of .net9 experimental dark app mode: SystemColorMode.Dark
The themeing is adopted to use Windows dark app mode enabled in .net9.
The .net9 dark mode does not allow override of any system colors.
A number of adaptions of the application colors.
There are some visual issues still, some due to .net,
but also the application colors may require some tuning.

Add dark+ theme, similar to VS Code Dark+ theme with darker panels and editor.

highconstrast_dark theme was removed, no longer needed

Refs: #12111

author highlight more subtle

Author: gerhardol

.editorconfig

@@ -296,7 +296,11 @@ csharp_style_allow_blank_line_after_token_in_arrow_expression_clause_experimenta
 csharp_style_prefer_pattern_matching = true:silent
 csharp_style_prefer_not_pattern = true:suggestion
 csharp_style_prefer_extended_property_pattern = true:suggestion
+csharp_prefer_system_threading_lock = true:suggestion
 
 # WFO1000: A property should determine its property content serialization with the DesignerSerializationVisibilityAttribute, DefaultValueAttribute or the ShouldSerializeProperty method
 # Silent for now, see https://github.com/dotnet/winforms/issues/12476
-dotnet_diagnostic.WFO1000.severity = silent
+dotnet_diagnostic.WFO1000.severity = silent
+
+# WFO5001: Type is for evaluation purposes only and is subject to change or removal in future updates. Suppress this diagnostic to proceed.
+dotnet_diagnostic.WFO5001.severity = silent

setup/installer/Product.wxs

@@ -314,8 +314,11 @@
       <Component Id="Themes.light_plus.css" Guid="*">
         <File Source="$(var.ArtifactsPublishPath)\Themes\light+.css" />
       </Component>
-      <Component Id="Themes.highcontrast_dark.css" Guid="*">
-        <File Source="$(var.ArtifactsPublishPath)\Themes\highcontrast_dark.css" />
+      <Component Id="Themes.dark.css" Guid="*">
+        <File Source="$(var.ArtifactsPublishPath)\Themes\dark.css" />
+      </Component>
+      <Component Id="Themes.dark_plus.css" Guid="*">
+        <File Source="$(var.ArtifactsPublishPath)\Themes\dark+.css" />
       </Component>
     </DirectoryRef>
     <DirectoryRef Id="PluginsDir">
@@ -606,8 +609,9 @@
     <ComponentGroup Id="Component.Themes">
       <ComponentRef Id="Themes.README.md" />
       <ComponentRef Id="Themes.invariant.css" />
-      <ComponentRef Id="Themes.highcontrast_dark.css" />
       <ComponentRef Id="Themes.light_plus.css" />
+      <ComponentRef Id="Themes.dark.css" />
+      <ComponentRef Id="Themes.dark_plus.css" />
     </ComponentGroup>
     <ComponentGroup Id="Component.Translation">
       <ComponentRef Id="English.gif" />

src/app/BugReporter/BugReportForm.cs

@@ -14,6 +14,7 @@
 using GitExtensions.Extensibility.Translations;
 using GitExtensions.Extensibility.Translations.Xliff;
 using GitExtUtils.GitUI;
+using GitExtUtils.GitUI.Theming;
 using GitUI;
 using Microsoft;
 using ResourceManager;
@@ -126,6 +127,12 @@ public DialogResult ShowDialog(IWin32Window? owner, SerializableException except
             return result;
         }
 
+        protected override void OnLoad(EventArgs e)
+        {
+            base.OnLoad(e);
+            this.FixVisualStyle();
+        }
+
         protected override void OnShown(EventArgs e)
         {
             base.OnShown(e);

src/app/GitExtUtils/GitUI/Theming/AppColorDefaults.cs

@@ -58,7 +58,7 @@ public static class AppColorDefaults
                 { AppColor.AnsiTerminalWhiteForeNormal, Color.FromArgb(0xbf, 0xbf, 0xbf) },
                 { AppColor.AnsiTerminalWhiteBackNormal, Color.FromArgb(0xe0, 0xe0, 0xe0) },
                 { AppColor.AnsiTerminalWhiteForeBold, Color.FromArgb(0xff, 0xff, 0xff) },
-                { AppColor.AnsiTerminalWhiteBackBold, Color.FromArgb(0xff, 0xff, 0xff) }
+                { AppColor.AnsiTerminalWhiteBackBold, Color.FromArgb(0xff, 0xff, 0xff) },
             };
 
         private static readonly Dictionary<string, Dictionary<AppColor, Color>> _variations = new()

src/app/GitExtUtils/GitUI/Theming/Theme.cs

@@ -55,7 +55,7 @@ private Color GetSysColor(KnownColor name) =>
         /// </summary>
         private static IReadOnlyCollection<KnownColor> SysColorNames { get; } =
             new HashSet<KnownColor>(
-                Enum.GetValues(typeof(KnownColor))
+                Enum.GetValues<KnownColor>()
                     .Cast<KnownColor>()
                     .Where(c => IsSystemColor(c)));
 

src/app/GitExtUtils/GitUI/Theming/ThemeFix.cs

@@ -21,8 +21,8 @@ public static void FixVisualStyle(this Control container)
                 return;
             }
 
-            container.DescendantsToFix<GroupBox>()
-                 .ForEach(SetupGroupBox);
+            container.DescendantsToFix<DataGridView>()
+                .ForEach(SetupDataGridView);
             container.DescendantsToFix<TreeView>()
                 .ForEach(SetupTreeView);
             container.DescendantsToFix<TabControl>()
@@ -33,6 +33,8 @@ public static void FixVisualStyle(this Control container)
                 .ForEach(SetupLinkLabel);
             container.DescendantsToFix<ToolStrip>()
                 .ForEach(SetupToolStrip);
+            container.DescendantsToFix<Button>()
+                .ForEach(SetupButton);
             container.ContextMenusToFix()
                 .ForEach(SetupContextMenu);
         }
@@ -81,9 +83,15 @@ private static void SetupLinkLabel(this LinkLabel label)
             label.ActiveLinkColor = label.ActiveLinkColor.AdaptTextColor();
         }
 
-        private static void SetupGroupBox(this GroupBox box)
+        private static void SetupButton(this Button button)
         {
-            box.TouchForeColor();
+            // .net9 fix for https://github.com/dotnet/winforms/issues/11949 (only supposed to occur for 100%)
+            if (Application.IsDarkModeEnabled && button.FlatStyle == FlatStyle.Standard)
+            {
+                // In addition to not setting the BackColor (TouchBackColor() will fix),
+                // FlatStyle.Standard buttons look ugly in dark mode
+                button.FlatStyle = FlatStyle.Flat;
+            }
         }
 
         private static void SetupTabControl(TabControl tabControl)
@@ -101,6 +109,12 @@ private static void SetupTabPage(TabPage page)
             }
         }
 
+        private static void SetupDataGridView(DataGridView view)
+        {
+            view.EnableHeadersVisualStyles = false;
+            view.ColumnHeadersDefaultCellStyle.BackColor = view.ColumnHeadersDefaultCellStyle.BackColor;
+        }
+
         private static void SetupTreeView(TreeView view)
         {
         }

src/app/GitUI/CommandsDialogs/BrowseDialog/DashboardControl/Dashboard.cs

@@ -4,7 +4,6 @@
 using GitExtUtils.GitUI;
 using GitExtUtils.GitUI.Theming;
 using GitUI.Properties;
-using GitUI.Theming;
 using ResourceManager;
 
 namespace GitUI.CommandsDialogs.BrowseDialog.DashboardControl
@@ -56,7 +55,7 @@ protected override void OnVisibleChanged(EventArgs e)
 
         public void RefreshContent()
         {
-            DashboardTheme selectedTheme = ThemeModule.IsDarkTheme ? DashboardTheme.Dark : DashboardTheme.Light;
+            DashboardTheme selectedTheme = Application.IsDarkModeEnabled ? DashboardTheme.Dark : DashboardTheme.Light;
 
             InitDashboardLayout();
             ApplyTheme();

src/app/GitUI/CommandsDialogs/FormCommit.cs

@@ -205,10 +205,13 @@ private CommitKind CommitKind
                 _commitKind = value;
 
                 modifyCommitMessageButton.Visible = _useFormCommitMessage && CommitKind is not (CommitKind.Normal or CommitKind.Amend);
+                modifyCommitMessageButton.ForeColor = Application.IsDarkModeEnabled ? SystemColors.ControlText : SystemColors.HotTrack;
+
                 bool messageCanBeChanged = _useFormCommitMessage && CommitKind is (CommitKind.Normal or CommitKind.Amend);
                 Message.Enabled = messageCanBeChanged;
                 commitMessageToolStripMenuItem.Enabled = messageCanBeChanged;
                 commitTemplatesToolStripMenuItem.Enabled = messageCanBeChanged;
+                Message.EvaluateForecolor();
             }
         }
 
@@ -348,6 +351,10 @@ public FormCommit(IGitUICommands commands, CommitKind commitKind = CommitKind.No
 
             toolStripStatusBranchIcon.AdaptImageLightness();
 
+            // Change the link color
+            commitAuthorStatus.LinkColor = Application.IsDarkModeEnabled ? Color.CornflowerBlue : Color.FromArgb(0, 0, 0xff);
+            remoteNameLabel.LinkColor = Application.IsDarkModeEnabled ? Color.CornflowerBlue : Color.Blue;
+
             splitLeft.Panel1.BackColor = OtherColors.PanelBorderColor;
             splitLeft.Panel2.BackColor = OtherColors.PanelBorderColor;
             splitRight.Panel1.BackColor = OtherColors.PanelBorderColor;

src/app/GitUI/CommandsDialogs/FormRebase.cs

@@ -195,7 +195,7 @@ private void EnableButtons()
                 AcceptButton = btnSolveConflicts;
                 btnSolveConflicts.Focus();
                 btnSolveConflicts.Text = _solveConflictsText2.Text;
-                MergeToolPanel.BackColor = Color.Yellow.AdaptBackColor();
+                MergeToolPanel.BackColor = Application.IsDarkModeEnabled ? Color.FromArgb(136, 136, 0) : Color.Yellow.AdaptBackColor();
             }
             else if (Module.InTheMiddleOfRebase())
             {

src/app/GitUI/CommandsDialogs/SettingsDialog/Pages/ScriptsSettingsPage.cs

@@ -7,7 +7,6 @@
 using GitCommands.Utils;
 using GitExtUtils;
 using GitExtUtils.GitUI;
-using GitExtUtils.GitUI.Theming;
 using GitUI.ScriptsEngine;
 using Microsoft;
 using ResourceManager;
@@ -177,7 +176,7 @@ public override void OnPageShown()
                 {
                     if (icon.Value is Bitmap bitmap)
                     {
-                        EmbeddedIcons.Images.Add(icon.Key.ToString()!, bitmap.AdaptLightness());
+                        EmbeddedIcons.Images.Add(icon.Key.ToString()!, bitmap);
                     }
                 }
 

src/app/GitUI/Editor/Diff/AnsiEscapeUtilities.cs

@@ -1,5 +1,4 @@
 using System.Diagnostics;
-using System.Linq;
 using System.Text;
 using System.Text.RegularExpressions;
 using GitExtensions.Extensibility;
@@ -13,7 +12,7 @@ public partial class AnsiEscapeUtilities
 {
     [GeneratedRegex(@"\u001b\[((?<escNo>\d+)\s*[:;]?\s*)*m", RegexOptions.ExplicitCapture)]
     private static partial Regex EscapeRegex();
-    private static readonly int _defaultForeColorId = ThemeModule.IsDarkTheme ? _whiteId : _blackId;
+    private static readonly int _defaultForeColorId = Application.IsDarkModeEnabled ? _whiteId : _blackId;
 
     // Color code definitions
     private const int _blackId = 0;

src/app/GitUI/Editor/FileViewer.cs

@@ -16,7 +16,6 @@
 using GitUI.CommandsDialogs;
 using GitUI.CommandsDialogs.SettingsDialog.Pages;
 using GitUI.Properties;
-using GitUI.Theming;
 using GitUI.UserControls;
 using GitUIPluginInterfaces;
 using ICSharpCode.TextEditor.Util;
@@ -436,7 +435,9 @@ public ArgumentString GetExtraDiffArguments(bool isRangeDiff = false, bool isCom
             // Difftastic coloring is always used (AppSettings.UseGitColoring.Value is not used).
             // Allow user to override with difftool command line options.
             SetEnvironmentVariable("DFT_COLOR", "always");
-            SetEnvironmentVariable("DFT_BACKGROUND", ThemeModule.IsDarkTheme ? "dark" : "light");
+
+            // DFT_BACKGROUND="dark" applies bold-bold colors, "light" corresponds better with Git colors
+            SetEnvironmentVariable("DFT_BACKGROUND", "light");
             SetEnvironmentVariable("DFT_SYNTAX_HIGHLIGHT", ShowSyntaxHighlightingInDiff ? "on" : "off");
             int contextLines = ShowEntireFile ? 9000 : NumberOfContextLines;
             SetEnvironmentVariable("DFT_CONTEXT", contextLines.ToString());

src/app/GitUI/Editor/GitHighlightingStrategyBase.cs

@@ -1,5 +1,4 @@
 using GitExtensions.Extensibility.Git;
-using GitExtUtils.GitUI.Theming;
 using ICSharpCode.TextEditor.Document;
 
 namespace GitUI.Editor

src/app/GitUI/Editor/RebaseTodoHighlightingStrategy.cs

@@ -1,5 +1,4 @@
 using GitExtensions.Extensibility.Git;
-using GitExtUtils.GitUI.Theming;
 using ICSharpCode.TextEditor;
 using ICSharpCode.TextEditor.Document;
 
@@ -18,15 +17,15 @@ internal sealed class RebaseTodoHighlightingStrategy : GitHighlightingStrategyBa
         d, drop = remove commit
         */
 
-        private static readonly Dictionary<char, (string longForm, HighlightColor color, string[] options)> _commandByFirstChar = new()
+        private readonly Dictionary<char, (string longForm, HighlightColor color, string[] options)> _commandByFirstChar = new()
         {
             { 'p', ("pick", new HighlightColor(nameof(SystemColors.InfoText), bold: true, italic: false), Array.Empty<string>()) },
-            { 'r', ("reword", new HighlightColor(Color.Purple.AdaptTextColor(), bold: true, italic: false), Array.Empty<string>()) },
-            { 'e', ("edit", new HighlightColor(Color.DarkGray.AdaptTextColor(), bold: true, italic: false), Array.Empty<string>()) },
-            { 's', ("squash", new HighlightColor(Color.DarkBlue.AdaptTextColor(), bold: true, italic: false), Array.Empty<string>()) },
-            { 'f', ("fixup", new HighlightColor(Color.LightCoral.AdaptTextColor(), bold: true, italic: false), new[] { "-C", "-c" }) },
+            { 'r', ("reword", new HighlightColor(Application.IsDarkModeEnabled ? Color.MediumPurple : Color.Purple, bold: true, italic: false, adaptable: false), Array.Empty<string>()) },
+            { 'e', ("edit", new HighlightColor(Application.IsDarkModeEnabled ? Color.LightGray : Color.DarkGray, bold: true, italic: false, adaptable: false), Array.Empty<string>()) },
+            { 's', ("squash", new HighlightColor(Application.IsDarkModeEnabled ? Color.CornflowerBlue : Color.DarkBlue, bold: true, italic: false, adaptable: false), Array.Empty<string>()) },
+            { 'f', ("fixup", new HighlightColor(Application.IsDarkModeEnabled ? Color.Coral : Color.LightCoral, bold: true, italic: false, adaptable: false), new[] { "-C", "-c" }) },
             { 'x', ("exec", new HighlightColor(nameof(SystemColors.GrayText), bold: true, italic: false), Array.Empty<string>()) },
-            { 'd', ("drop", new HighlightColor(Color.Red.AdaptTextColor(), bold: true, italic: false), Array.Empty<string>()) }
+            { 'd', ("drop", new HighlightColor(Application.IsDarkModeEnabled ? Color.IndianRed : Color.Red, bold: true, italic: false, adaptable: false), Array.Empty<string>()) }
         };
 
         public RebaseTodoHighlightingStrategy(IGitModule module)
@@ -57,7 +56,7 @@ private enum State
             Id
         }
 
-        private static bool TryHighlightInteractiveRebaseCommand(IDocument document, LineSegment line)
+        private bool TryHighlightInteractiveRebaseCommand(IDocument document, LineSegment line)
         {
             if (line.Length < 1)
             {

src/app/GitUI/GitUI.csproj

@@ -82,10 +82,4 @@
     </Content>
   </ItemGroup>
 
-  <ItemGroup>
-    <Content Update="Themes\dark.css">
-      <CopyToOutputDirectory>Never</CopyToOutputDirectory>
-    </Content>
-  </ItemGroup>
-
 </Project>

src/app/GitUI/LeftPanel/BaseRevisionNode.cs

@@ -1,6 +1,5 @@
 using System.Diagnostics;
 using GitExtensions.Extensibility.Git;
-using GitExtUtils.GitUI.Theming;
 using GitUI.Properties;
 
 namespace GitUI.LeftPanel
@@ -9,7 +8,7 @@ namespace GitUI.LeftPanel
     internal abstract class BaseRevisionNode : Node
     {
         protected const char PathSeparator = '/';
-        private static readonly Color _invisibleForeColor = Color.Silver.AdaptTextColor();
+        private static readonly Color _invisibleForeColor = Application.IsDarkModeEnabled ? SystemColors.GrayText : Color.Silver;
 
         protected BaseRevisionNode(Tree tree, string fullPath, bool visible)
             : base(tree)

src/app/GitUI/ScriptsEngine/SplitButton.cs

@@ -292,21 +292,17 @@ protected override void OnPaint(PaintEventArgs pevent)
 
             Graphics g = pevent.Graphics;
             Rectangle bounds = ClientRectangle;
+            pevent.Graphics.Clear(SystemColors.Window);
 
             // draw the button background as according to the current state.
             if (State != PushButtonState.Pressed && IsDefault && !Application.RenderWithVisualStyles)
             {
                 Rectangle backgroundBounds = bounds;
                 backgroundBounds.Inflate(-1, -1);
-                ButtonRenderer.DrawButton(g, backgroundBounds, State);
 
                 // button renderer doesn't draw the black frame when themes are off
                 g.DrawRectangle(SystemPens.WindowFrame, 0, 0, bounds.Width - 1, bounds.Height - 1);
             }
-            else
-            {
-                ButtonRenderer.DrawButton(g, bounds, State);
-            }
 
             // calculate the current dropdown rectangle.
             _dropDownRectangle = new Rectangle(bounds.Right - SplitSectionWidth, 0, SplitSectionWidth, bounds.Height);

src/app/GitUI/SpellChecker/EditNetSpell.cs

@@ -92,12 +92,23 @@ public override string Text
             set
             {
                 HideWatermark();
+                EvaluateForecolor();
                 TextBox.Text = value;
                 ShowWatermark();
                 OnTextAssigned();
             }
         }
 
+        public void EvaluateForecolor()
+        {
+            if (Application.IsDarkModeEnabled)
+            {
+                // In dark mode the background color is set to White, but still reported as SystemColors.Window (or adjusted)
+                // The Forecolor must be changed manually
+                TextBox.ForeColor = TextBox.Enabled ? SystemColors.WindowText : SystemColors.HighlightText;
+            }
+        }
+
         private void OnTextAssigned()
         {
             TextAssigned?.Invoke(this, EventArgs.Empty);