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Fix GroupBox doesn't apply ForeColor in ambient condition #14638

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Fix GroupBox doesn't apply ForeColor in ambient condition #14638

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f40e9bf
Added fix for issue 9958
Sathish-087 Jun 8, 2026
e90871a
Updated the review changes
Sathish-087 Jun 8, 2026
fcb60e1
Address Review changes and Added Test Cases
Sathish-087 Jun 19, 2026
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16 changes: 15 additions & 1 deletion src/System.Windows.Forms/System/Windows/Forms/Controls/GroupBox/GroupBox.cs
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Expand Up @@ -440,13 +440,27 @@ protected override void OnPaint(PaintEventArgs e)
}
else
{
GroupBoxRenderer.DrawGroupBox(
if (FindForm() is Form form && form.ForeColor != SystemColors.ControlText)

@Sathish-087 Sathish-087 Jun 19, 2026

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Added three unit tests covering: ambient ForeColor inherited from a Form, ambient ForeColor inherited from an intermediate Panel (the exact scenario FindForm() would have missed), and explicit ForeColor taking precedence over any ambient value.

@LeafShi1 LeafShi1 Jun 17, 2026

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  1. The fix uses FindForm() which jumps directly to the top-level Form. If the GroupBox is inside a Panel or UserControl that has a custom ForeColor, the ambient color from that intermediate parent is ignored.

    WinForms ambient property inheritance walks the full parent chain. this.ForeColor already returns the correct inherited value from any ancestor. A simpler and more correct fix would be to check whether the inherited ForeColor differs from the default

  2. form.ForeColor != SystemColors.ControlText assumes the default form ForeColor is always SystemColors.ControlText. If a high-contrast theme or custom Windows theme changes the default, this comparison could produce incorrect results

@Sathish-087 Sathish-087 Jun 19, 2026

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Thank you for the feedback! Both points have been addressed:

  • Replaced FindForm() with this.ForeColor, which already walks the full parent chain via WinForms ambient property inheritance — so intermediate parents with a custom ForeColor are correctly respected.
  • Replaced the form.ForeColor != SystemColors.ControlText comparison with ForeColor != DefaultForeColor. DefaultForeColor is theme-aware and resolves correctly under high-contrast and custom Windows themes.

{
GroupBoxRenderer.DrawGroupBox(
e,
new Rectangle(0, 0, Width, Height),
Text,
Font,
form.ForeColor,
textFlags,
gbState);
}
else
{
GroupBoxRenderer.DrawGroupBox(
e,
new Rectangle(0, 0, Width, Height),
Text,
Font,
textFlags,
gbState);
}

@Sathish-087 Sathish-087 Jun 19, 2026

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Replaced FindForm() with this.ForeColor, which already walks the full parent chain via WinForms ambient property inheritance — so intermediate parents with a custom ForeColor are correctly respected.

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}
}

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