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Fix issue 14859: CheckBox and RadioButton ignore explicit BackColor values in VisualStylesMode.Net11 #14865

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Fix issue 14859: CheckBox and RadioButton ignore explicit BackColor values in VisualStylesMode.Net11 #14865

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9fd5f98
Fix issue 14859: CheckBox and RadioButton ignore explicit BackColor v…
Aug 7, 2026
a7e2280
Merge branch 'main' into Fix_Issue_14859
Aug 10, 2026
d95d37f
Sync the latest code and apply relevant fixes.
Aug 10, 2026
4f776d3
Handle feedback
Aug 17, 2026
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43 changes: 30 additions & 13 deletions ...ndows.Forms/System/Windows/Forms/Controls/Buttons/ButtonInternal/CheckBoxModernAdapter.cs
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Original file line number Diff line number Diff line change
@@ -1,4 +1,4 @@
// Licensed to the .NET Foundation under one or more agreements.
// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.

using System.Drawing;
Expand Down Expand Up @@ -80,21 +80,33 @@ internal override LayoutOptions CommonLayout()
private void PaintCore(PaintEventArgs e)
{
Graphics graphics = e.GraphicsInternal;
ParentBackgroundRenderer.Paint(
Control,
graphics,
Control.ClientRectangle,
Control.BackColor);
bool useExplicitBackColor = Control.ShouldSerializeBackColor() || !Control.UseVisualStyleBackColor;
bool hasTransparentBackColor = Control.BackColor.HasTransparency();

if (useExplicitBackColor && !hasTransparentBackColor)
{
using var backBrush = Control.BackColor.GetCachedSolidBrushScope();
graphics.FillRectangle(backBrush, Control.ClientRectangle);
}
else
{
ParentBackgroundRenderer.Paint(
Control,
graphics,
Control.ClientRectangle,
Control.BackColor);

if (useExplicitBackColor && hasTransparentBackColor && Control.BackColor.A > 0)
{
using var backBrush = Control.BackColor.GetCachedSolidBrushScope();
graphics.FillRectangle(backBrush, Control.ClientRectangle);
}
}

LayoutData layout = Layout(e).Layout();
AdjustFocusRectangle(layout);
PaintBackgroundImage(e);

Color? customOnColor = Control.ShouldSerializeBackColor()
&& Control.BackColor.A == byte.MaxValue
? Control.BackColor
: null;

Color? customBorderColor = Control.FlatAppearance.BorderColor.IsEmpty
? null
: Control.FlatAppearance.BorderColor;
Expand All @@ -107,7 +119,7 @@ private void PaintCore(PaintEventArgs e)
Control.Enabled,
Control.MouseIsOver,
Control.Focused && Control.ShowFocusCues,
customOnColor,
customOnColor: null,
customBorderColor);

PaintImage(e, layout);
Expand All @@ -117,11 +129,16 @@ private void PaintCore(PaintEventArgs e)
: Application.IsDarkModeEnabled
? Color.FromArgb(0xF0, 0xF0, 0xF0)
: SystemColors.WindowText;
Color disabledTextBackColor = Control.ShouldSerializeBackColor()
&& Control.BackColor.A == byte.MaxValue
? Control.BackColor
: Control.Parent?.BackColor ?? Control.BackColor;

Color textColor = Control.Enabled
? preferredTextColor
: ModernControlColorMath.GetDisabledTextColor(
preferredTextColor,
Control.Parent?.BackColor ?? Control.BackColor);
disabledTextBackColor);

PaintField(e, layout, PaintRender(e).Calculate(), textColor, drawFocus: true);
}
Expand Down
43 changes: 30 additions & 13 deletions ...ws.Forms/System/Windows/Forms/Controls/Buttons/ButtonInternal/RadioButtonModernAdapter.cs
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Original file line number Diff line number Diff line change
@@ -1,4 +1,4 @@
// Licensed to the .NET Foundation under one or more agreements.
// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.

using System.Drawing;
Expand Down Expand Up @@ -79,21 +79,33 @@ internal override LayoutOptions CommonLayout()
private void PaintCore(PaintEventArgs e)
{
Graphics graphics = e.GraphicsInternal;
ParentBackgroundRenderer.Paint(
Control,
graphics,
Control.ClientRectangle,
Control.BackColor);
bool useExplicitBackColor = Control.ShouldSerializeBackColor() || !Control.UseVisualStyleBackColor;
bool hasTransparentBackColor = Control.BackColor.HasTransparency();

if (useExplicitBackColor && !hasTransparentBackColor)
{
using var backBrush = Control.BackColor.GetCachedSolidBrushScope();
graphics.FillRectangle(backBrush, Control.ClientRectangle);
}
else
{
ParentBackgroundRenderer.Paint(
Control,
graphics,
Control.ClientRectangle,
Control.BackColor);

if (useExplicitBackColor && hasTransparentBackColor && Control.BackColor.A > 0)
{
using var backBrush = Control.BackColor.GetCachedSolidBrushScope();
graphics.FillRectangle(backBrush, Control.ClientRectangle);
}
}

LayoutData layout = Layout(e).Layout();
AdjustFocusRectangle(layout);
PaintBackgroundImage(e);

Color? customOnColor = Control.ShouldSerializeBackColor()
&& Control.BackColor.A == byte.MaxValue
? Control.BackColor
: null;

Color? customBorderColor = Control.FlatAppearance.BorderColor.IsEmpty
? null
: Control.FlatAppearance.BorderColor;
Expand All @@ -106,7 +118,7 @@ private void PaintCore(PaintEventArgs e)
Control.Enabled,
Control.MouseIsOver,
Control.Focused && Control.ShowFocusCues,
customOnColor,
customOnColor: null,
customBorderColor);

PaintImage(e, layout);
Expand All @@ -116,11 +128,16 @@ private void PaintCore(PaintEventArgs e)
: Application.IsDarkModeEnabled
? Color.FromArgb(0xF0, 0xF0, 0xF0)
: SystemColors.WindowText;
Color disabledTextBackColor = Control.ShouldSerializeBackColor()
&& Control.BackColor.A == byte.MaxValue
? Control.BackColor
: Control.Parent?.BackColor ?? Control.BackColor;

Color textColor = Control.Enabled
? preferredTextColor
: ModernControlColorMath.GetDisabledTextColor(
preferredTextColor,
Control.Parent?.BackColor ?? Control.BackColor);
disabledTextBackColor);

PaintField(e, layout, PaintRender(e).Calculate(), textColor, drawFocus: true);
}
Expand Down
87 changes: 84 additions & 3 deletions src/test/unit/System.Windows.Forms/System/Windows/Forms/CheckBoxTests.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -571,17 +571,24 @@ public void CheckBox_AppearanceChanged_RecreatesModernAdapter()
[InlineData(CheckState.Unchecked, false)]
[InlineData(CheckState.Checked, true)]
[InlineData(CheckState.Indeterminate, true)]
public void CheckBox_ModernGlyph_RendersAccentForCheckedStates(CheckState checkState, bool expectedAccent)
public void CheckBox_ModernGlyph_UsesExplicitBackColorWithoutTintingCheckedGlyph(CheckState checkState, bool expectedAccent)
{
if (SystemInformation.HighContrast)
{
return;
}

Color accentColor = Application.SystemVisualSettings.AccentColor;
Color backgroundColor = Color.FromArgb(
accentColor.R ^ 0xFF,
accentColor.G ^ 0xFF,
accentColor.B ^ 0xFF);

using Panel parent = new() { BackColor = Color.White };
using CheckBox box = new()
{
BackColor = Color.Red,
BackColor = backgroundColor,
UseVisualStyleBackColor = true,
CheckState = checkState,
Size = new Size(40, 24),
VisualStylesMode = VisualStylesMode.Net11
Expand All @@ -594,7 +601,69 @@ public void CheckBox_ModernGlyph_RendersAccentForCheckedStates(CheckState checkS

box.CreateStandardAdapter().PaintUp(e, checkState);

Assert.Equal(expectedAccent, CountPixels(bitmap, Color.Red) > 0);
Color backgroundPixel = bitmap.GetPixel(box.Width - 2, box.Height / 2);
Assert.Equal(backgroundColor.ToArgb(), backgroundPixel.ToArgb());
Assert.Equal(
expectedAccent,
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CountPixels(bitmap, accentColor) > 0);
}

[WinFormsFact]
public void CheckBox_ModernGlyph_UsesExplicitBackColorWhenVisualStyleBackgroundDisabled()
{
using Panel parent = new() { BackColor = Color.White };
using CheckBox box = new()
{
BackColor = Color.Aqua,
CheckState = CheckState.Unchecked,
Text = string.Empty,
Size = new Size(40, 24),
VisualStylesMode = VisualStylesMode.Net11
};

parent.Controls.Add(box);

using Bitmap bitmap = new(box.Width, box.Height);
using Graphics graphics = Graphics.FromImage(bitmap);
PaintEventArgs e = new(graphics, box.ClientRectangle);

box.CreateStandardAdapter().PaintUp(e, box.CheckState);

Color backgroundPixel = bitmap.GetPixel(box.Width - 2, box.Height / 2);
Assert.Equal(Color.Aqua.ToArgb(), backgroundPixel.ToArgb());
}

[WinFormsFact]
public void CheckBox_ModernGlyph_UsesTranslucentBackColorWhenVisualStyleBackgroundEnabled()
{
Color parentBackColor = Color.White;
Color translucentBackColor = Color.FromArgb(128, Color.Aqua);

using Panel parent = new() { BackColor = parentBackColor };
using CheckBox box = new()
{
BackColor = translucentBackColor,
UseVisualStyleBackColor = true,
CheckState = CheckState.Unchecked,
Text = string.Empty,
Size = new Size(40, 24),
VisualStylesMode = VisualStylesMode.Net11
};

parent.Controls.Add(box);

using Bitmap bitmap = new(box.Width, box.Height);
using Graphics graphics = Graphics.FromImage(bitmap);
graphics.Clear(parentBackColor);
PaintEventArgs e = new(graphics, box.ClientRectangle);

box.CreateStandardAdapter().PaintUp(e, box.CheckState);

Color backgroundPixel = bitmap.GetPixel(box.Width - 2, box.Height / 2);
Color expected = BlendColors(parentBackColor, translucentBackColor);
Assert.InRange(Math.Abs(backgroundPixel.R - expected.R), 0, 1);
Assert.InRange(Math.Abs(backgroundPixel.G - expected.G), 0, 1);
Assert.InRange(Math.Abs(backgroundPixel.B - expected.B), 0, 1);
}

[WinFormsFact]
Expand Down Expand Up @@ -1034,6 +1103,18 @@ private static int CountPixels(Bitmap bitmap, Color color)
return count;
}

private static Color BlendColors(Color background, Color overlay)
{
int alpha = overlay.A;
int inverseAlpha = byte.MaxValue - alpha;

int red = ((overlay.R * alpha) + (background.R * inverseAlpha) + 127) / 255;
int green = ((overlay.G * alpha) + (background.G * inverseAlpha) + 127) / 255;
int blue = ((overlay.B * alpha) + (background.B * inverseAlpha) + 127) / 255;

return Color.FromArgb(red, green, blue);
}

[WinFormsFact]
public void CheckBox_GetAutoSizeMode_Invoke_ReturnsExpected()
{
Expand Down
87 changes: 84 additions & 3 deletions src/test/unit/System.Windows.Forms/System/Windows/Forms/RadioButtonTests.cs
View file
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Original file line number Diff line number Diff line change
Expand Up @@ -209,17 +209,24 @@ public void RadioButton_AppearanceChanged_RecreatesModernAdapter()
[WinFormsTheory]
[InlineData(false, false)]
[InlineData(true, true)]
public void RadioButton_ModernGlyph_RendersAccentWhenChecked(bool isChecked, bool expectedAccent)
public void RadioButton_ModernGlyph_UsesExplicitBackColorWithoutTintingCheckedGlyph(bool isChecked, bool expectedAccent)
{
if (SystemInformation.HighContrast)
{
return;
}

Color accentColor = Application.SystemVisualSettings.AccentColor;
Color backgroundColor = Color.FromArgb(
accentColor.R ^ 0xFF,
accentColor.G ^ 0xFF,
accentColor.B ^ 0xFF);

using Panel parent = new() { BackColor = Color.White };
using RadioButton control = new()
{
BackColor = Color.Red,
BackColor = backgroundColor,
UseVisualStyleBackColor = true,
Checked = isChecked,
Size = new Size(40, 24),
VisualStylesMode = VisualStylesMode.Net11
Expand All @@ -234,7 +241,69 @@ public void RadioButton_ModernGlyph_RendersAccentWhenChecked(bool isChecked, boo
e,
isChecked ? CheckState.Checked : CheckState.Unchecked);

Assert.Equal(expectedAccent, CountPixels(bitmap, Color.Red) > 0);
Color backgroundPixel = bitmap.GetPixel(control.Width - 2, control.Height / 2);
Assert.Equal(backgroundColor.ToArgb(), backgroundPixel.ToArgb());
Assert.Equal(
expectedAccent,
CountPixels(bitmap, accentColor, channelTolerance: 24) > 0);
}

[WinFormsFact]
public void RadioButton_ModernGlyph_UsesExplicitBackColorWhenVisualStyleBackgroundDisabled()
{
using Panel parent = new() { BackColor = Color.White };
using RadioButton control = new()
{
BackColor = Color.Aqua,
Checked = false,
Text = string.Empty,
Size = new Size(40, 24),
VisualStylesMode = VisualStylesMode.Net11
};

parent.Controls.Add(control);

using Bitmap bitmap = new(control.Width, control.Height);
using Graphics graphics = Graphics.FromImage(bitmap);
PaintEventArgs e = new(graphics, control.ClientRectangle);

control.CreateStandardAdapter().PaintUp(e, CheckState.Unchecked);

Color backgroundPixel = bitmap.GetPixel(control.Width - 2, control.Height / 2);
Assert.Equal(Color.Aqua.ToArgb(), backgroundPixel.ToArgb());
}

[WinFormsFact]
public void RadioButton_ModernGlyph_UsesTranslucentBackColorWhenVisualStyleBackgroundEnabled()
{
Color parentBackColor = Color.White;
Color translucentBackColor = Color.FromArgb(128, Color.Aqua);

using Panel parent = new() { BackColor = parentBackColor };
using RadioButton control = new()
{
BackColor = translucentBackColor,
UseVisualStyleBackColor = true,
Checked = false,
Text = string.Empty,
Size = new Size(40, 24),
VisualStylesMode = VisualStylesMode.Net11
};

parent.Controls.Add(control);

using Bitmap bitmap = new(control.Width, control.Height);
using Graphics graphics = Graphics.FromImage(bitmap);
graphics.Clear(parentBackColor);
PaintEventArgs e = new(graphics, control.ClientRectangle);

control.CreateStandardAdapter().PaintUp(e, CheckState.Unchecked);

Color backgroundPixel = bitmap.GetPixel(control.Width - 2, control.Height / 2);
Color expected = BlendColors(parentBackColor, translucentBackColor);
Assert.InRange(Math.Abs(backgroundPixel.R - expected.R), 0, 1);
Assert.InRange(Math.Abs(backgroundPixel.G - expected.G), 0, 1);
Assert.InRange(Math.Abs(backgroundPixel.B - expected.B), 0, 1);
}

[WinFormsFact]
Expand Down Expand Up @@ -373,6 +442,18 @@ public void RadioButton_ModernGlyph_EndAnimation_StopsAndSettles()
private static int CountPixels(Bitmap bitmap, Color color)
=> CountPixels(bitmap, color, channelTolerance: 0);

private static Color BlendColors(Color background, Color overlay)
{
int alpha = overlay.A;
int inverseAlpha = byte.MaxValue - alpha;

int red = ((overlay.R * alpha) + (background.R * inverseAlpha) + 127) / 255;
int green = ((overlay.G * alpha) + (background.G * inverseAlpha) + 127) / 255;
int blue = ((overlay.B * alpha) + (background.B * inverseAlpha) + 127) / 255;

return Color.FromArgb(red, green, blue);
}

private static int CountPixels(Bitmap bitmap, Color color, int channelTolerance)
{
int count = 0;
Expand Down