Fix ToolStripStatusLabel text visibility in High Contrast mode with System RenderMode

src/System.Windows.Forms/System/Windows/Forms/Controls/ToolStrips/ToolStripHighContrastRenderer.cs

@@ -173,6 +173,18 @@ protected override void OnRenderLabelBackground(ToolStripItemRenderEventArgs e)
         }
     }
 
+    protected override void OnRenderToolStripStatusLabelBackground(ToolStripItemRenderEventArgs e)
+    {
+        if (FillWhenSelected)
+        {
+            RenderItemInternalFilled(e);
+        }
+        else
+        {
+            base.OnRenderToolStripStatusLabelBackground(e);
+        }
+    }
+
     protected override void OnRenderMenuItemBackground(ToolStripItemRenderEventArgs e)
     {
         base.OnRenderMenuItemBackground(e);

src/System.Windows.Forms/System/Windows/Forms/Controls/ToolStrips/ToolStripSystemRenderer.cs

@@ -453,6 +453,14 @@ protected override void OnRenderOverflowButtonBackground(ToolStripItemRenderEven
     /// </summary>
     protected override void OnRenderLabelBackground(ToolStripItemRenderEventArgs e)
     {
+        // If system is in high contrast mode or dark mode and a specific renderer-override is defined, use that.
+        // For ToolStripSystemRenderer in a contrast theme, the RendererOverride property will be ToolStripHighContrastRenderer.
+        if (RendererOverride is not null)
+        {
+            base.OnRenderLabelBackground(e);
+            return;
+        }
+
         RenderLabelInternal(e);
     }
 
@@ -545,6 +553,14 @@ protected override void OnRenderSeparator(ToolStripSeparatorRenderEventArgs e)
 
     protected override void OnRenderToolStripStatusLabelBackground(ToolStripItemRenderEventArgs e)
     {
+        // If system is in high contrast mode or dark mode and a specific renderer-override is defined, use that.
+        // For ToolStripSystemRenderer in a contrast theme, the RendererOverride property will be ToolStripHighContrastRenderer.
+        if (RendererOverride is not null)
+        {
+            base.OnRenderToolStripStatusLabelBackground(e);
+            return;
+        }
+
         RenderLabelInternal(e);
         ToolStripStatusLabel? item = e.Item as ToolStripStatusLabel;
         if (item is not null)

src/test/unit/System.Windows.Forms/System/Windows/Forms/ToolStripLabelTests.Rendering.cs

@@ -0,0 +1,80 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+#nullable disable
+
+using System.Drawing;
+using System.Windows.Forms.Metafiles;
+
+namespace System.Windows.Forms.Tests;
+
+public partial class ToolStripLabelTests
+{
+    [WinFormsFact]
+    public void ToolStripLabel_Selected_RendersBackgroundCorrectly_HighContrast()
+    {
+        using Form form = new();
+        using ToolStrip toolStrip = new();
+        toolStrip.Renderer = new ToolStripSystemHighContrastRenderer();
+        using ToolStripLabel toolStripLabel = new()
+        {
+            IsLink = true,
+            Text = "Test Link"
+        };
+        toolStrip.Items.Add(toolStripLabel);
+        form.Controls.Add(toolStrip);
+        toolStripLabel.Select();
+
+        using EmfScope emf = new();
+        DeviceContextState state = new(emf);
+        Rectangle bounds = toolStripLabel.Bounds;
+        using PaintEventArgs e = new(emf, bounds);
+        toolStripLabel.TestAccessor().Dynamic.OnPaint(e);
+
+        // In high contrast mode, selected items should have a highlight background
+        emf.Validate(
+           state,
+           Validate.Polygon16(
+                bounds: null,
+                points: null,
+                State.Brush(SystemColors.Highlight, BRUSH_STYLE.BS_SOLID)),
+           Validate.Repeat(Validate.SkipType(ENHANCED_METAFILE_RECORD_TYPE.EMR_POLYPOLYGON16), 2));
+    }
+
+    [WinFormsFact]
+    public void ToolStripLabel_IsLink_Selected_RendersBackgroundCorrectly_HighContrast()
+    {
+        using Form form = new();
+        using ToolStrip toolStrip = new();
+        toolStrip.Renderer = new ToolStripSystemHighContrastRenderer();
+        using ToolStripLabel toolStripLabel = new()
+        {
+            IsLink = true,
+            Text = "Link Text"
+        };
+        toolStrip.Items.Add(toolStripLabel);
+        form.Controls.Add(toolStrip);
+        toolStripLabel.Select();
+
+        using EmfScope emf = new();
+        DeviceContextState state = new(emf);
+        Rectangle bounds = toolStripLabel.Bounds;
+        using PaintEventArgs e = new(emf, bounds);
+        toolStripLabel.TestAccessor().Dynamic.OnPaint(e);
+
+        // When IsLink is true and item is selected in high contrast mode,
+        // the background should be filled with highlight color for proper visibility
+        emf.Validate(
+           state,
+           Validate.Polygon16(
+                bounds: null,
+                points: null,
+                State.Brush(SystemColors.Highlight, BRUSH_STYLE.BS_SOLID)),
+           Validate.Repeat(Validate.SkipType(ENHANCED_METAFILE_RECORD_TYPE.EMR_POLYPOLYGON16), 2));
+    }
+
+    private class ToolStripSystemHighContrastRenderer : ToolStripSystemRenderer
+    {
+        internal override ToolStripRenderer RendererOverride => HighContrastRenderer;
+    }
+}

src/test/unit/System.Windows.Forms/System/Windows/Forms/ToolStripStatusLabelTests.Rendering.cs

@@ -0,0 +1,80 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+#nullable disable
+
+using System.Drawing;
+using System.Windows.Forms.Metafiles;
+
+namespace System.Windows.Forms.Tests;
+
+public partial class ToolStripStatusLabelTests
+{
+    [WinFormsFact]
+    public void ToolStripStatusLabel_Selected_RendersBackgroundCorrectly_HighContrast()
+    {
+        using Form form = new();
+        using StatusStrip statusStrip = new();
+        statusStrip.Renderer = new ToolStripSystemHighContrastRenderer();
+        using ToolStripStatusLabel toolStripStatusLabel = new()
+        {
+            IsLink = true,
+            Text = "Test Link"
+        };
+        statusStrip.Items.Add(toolStripStatusLabel);
+        form.Controls.Add(statusStrip);
+        toolStripStatusLabel.Select();
+
+        using EmfScope emf = new();
+        DeviceContextState state = new(emf);
+        Rectangle bounds = toolStripStatusLabel.Bounds;
+        using PaintEventArgs e = new(emf, bounds);
+        toolStripStatusLabel.TestAccessor().Dynamic.OnPaint(e);
+
+        // In high contrast mode, selected items should have a highlight background
+        emf.Validate(
+           state,
+           Validate.Polygon16(
+                bounds: null,
+                points: null,
+                State.Brush(SystemColors.Highlight, BRUSH_STYLE.BS_SOLID)),
+           Validate.Repeat(Validate.SkipType(ENHANCED_METAFILE_RECORD_TYPE.EMR_POLYPOLYGON16), 2));
+    }
+
+    [WinFormsFact]
+    public void ToolStripStatusLabel_IsLink_Selected_RendersBackgroundCorrectly_HighContrast()
+    {
+        using Form form = new();
+        using StatusStrip statusStrip = new();
+        statusStrip.Renderer = new ToolStripSystemHighContrastRenderer();
+        using ToolStripStatusLabel toolStripStatusLabel = new()
+        {
+            IsLink = true,
+            Text = "Link Text"
+        };
+        statusStrip.Items.Add(toolStripStatusLabel);
+        form.Controls.Add(statusStrip);
+        toolStripStatusLabel.Select();
+
+        using EmfScope emf = new();
+        DeviceContextState state = new(emf);
+        Rectangle bounds = toolStripStatusLabel.Bounds;
+        using PaintEventArgs e = new(emf, bounds);
+        toolStripStatusLabel.TestAccessor().Dynamic.OnPaint(e);
+
+        // When IsLink is true and item is selected in high contrast mode,
+        // the background should be filled with highlight color for proper visibility
+        emf.Validate(
+           state,
+           Validate.Polygon16(
+                bounds: null,
+                points: null,
+                State.Brush(SystemColors.Highlight, BRUSH_STYLE.BS_SOLID)),
+           Validate.Repeat(Validate.SkipType(ENHANCED_METAFILE_RECORD_TYPE.EMR_POLYPOLYGON16), 2));
+    }
+
+    private class ToolStripSystemHighContrastRenderer : ToolStripSystemRenderer
+    {
+        internal override ToolStripRenderer RendererOverride => HighContrastRenderer;
+    }
+}