From ee8a878e3be1fd73cbeb805e28a73d5f86a09590 Mon Sep 17 00:00:00 2001
From: "Simon Zhao (BEYONDSOFT CONSULTING INC)" <v-weidzh@microsoft.com>
Date: Tue, 7 Jul 2026 13:47:04 +0800
Subject: [PATCH 1/2] Fix issue 14025: [DarkMode] the item lost dot line when
 using the mouse to expand the dropdown panel for SelectionPanelRadioButton

---
 ...tionPanelBase.SelectionPanelRadioButton.cs | 22 +++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/src/System.Windows.Forms.Design/src/System/Drawing/SelectionPanelBase.SelectionPanelRadioButton.cs b/src/System.Windows.Forms.Design/src/System/Drawing/SelectionPanelBase.SelectionPanelRadioButton.cs
index 569930b5389..1d836934681 100644
--- a/src/System.Windows.Forms.Design/src/System/Drawing/SelectionPanelBase.SelectionPanelRadioButton.cs
+++ b/src/System.Windows.Forms.Design/src/System/Drawing/SelectionPanelBase.SelectionPanelRadioButton.cs
@@ -9,6 +9,8 @@ internal abstract partial class SelectionPanelBase
 {
     protected class SelectionPanelRadioButton : RadioButton
     {
+        private const int WM_PAINT = 0x000F;
+
         public SelectionPanelRadioButton()
         {
             AutoCheck = false;
@@ -16,6 +18,26 @@ public SelectionPanelRadioButton()
 
         protected override bool ShowFocusCues => true;
 
+        protected override void WndProc(ref Message m)
+        {
+            base.WndProc(ref m);
+
+            if (m.Msg != WM_PAINT || !Focused || !ShowFocusCues)
+            {
+                return;
+            }
+
+            Rectangle focusBounds = ClientRectangle;
+            focusBounds.Inflate(-3, -3);
+            if (focusBounds.Width <= 0 || focusBounds.Height <= 0)
+            {
+                return;
+            }
+
+            using Graphics g = CreateGraphics();
+            ControlPaint.DrawFocusRectangle(g, focusBounds, ForeColor, BackColor);
+        }
+
         protected override bool IsInputKey(Keys keyData) => keyData switch
         {
             Keys.Left or Keys.Right or Keys.Up or Keys.Down or Keys.Return => true,

From 17659c604083ce842c59d82fa874dcbf6bc7e97d Mon Sep 17 00:00:00 2001
From: "Simon Zhao (BEYONDSOFT CONSULTING INC)" <v-weidzh@microsoft.com>
Date: Tue, 7 Jul 2026 14:21:23 +0800
Subject: [PATCH 2/2] Handle feedback

---
 .../Drawing/SelectionPanelBase.SelectionPanelRadioButton.cs | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/src/System.Windows.Forms.Design/src/System/Drawing/SelectionPanelBase.SelectionPanelRadioButton.cs b/src/System.Windows.Forms.Design/src/System/Drawing/SelectionPanelBase.SelectionPanelRadioButton.cs
index 1d836934681..f28c0afd11b 100644
--- a/src/System.Windows.Forms.Design/src/System/Drawing/SelectionPanelBase.SelectionPanelRadioButton.cs
+++ b/src/System.Windows.Forms.Design/src/System/Drawing/SelectionPanelBase.SelectionPanelRadioButton.cs
@@ -9,8 +9,6 @@ internal abstract partial class SelectionPanelBase
 {
     protected class SelectionPanelRadioButton : RadioButton
     {
-        private const int WM_PAINT = 0x000F;
-
         public SelectionPanelRadioButton()
         {
             AutoCheck = false;
@@ -22,13 +20,13 @@ protected override void WndProc(ref Message m)
         {
             base.WndProc(ref m);
 
-            if (m.Msg != WM_PAINT || !Focused || !ShowFocusCues)
+            if (m.MsgInternal != PInvokeCore.WM_PAINT || !Focused || !ShowFocusCues)
             {
                 return;
             }
 
             Rectangle focusBounds = ClientRectangle;
-            focusBounds.Inflate(-3, -3);
+            focusBounds.Inflate(-LogicalToDeviceUnits(3), -LogicalToDeviceUnits(3));
             if (focusBounds.Width <= 0 || focusBounds.Height <= 0)
             {
                 return;