Fix The nodes of TreeView not in dark mode when editing it

src/System.Windows.Forms/System/Windows/Forms/Controls/ListView/ListView.cs

@@ -6973,6 +6973,18 @@ protected override void WndProc(ref Message m)
                 WmReflectNotify(ref m);
                 break;
 
+            case PInvokeCore.WM_CTLCOLOREDIT:
+                if (_labelEdit is not null && (HWND)m.LParamInternal == _labelEdit.HWND)
+                {
+                    m.ResultInternal = (LRESULT)(nint)InitializeDCForWmCtlColor((HDC)(nint)m.WParamInternal, m.MsgInternal);
+                }
+                else
+                {
+                    base.WndProc(ref m);
+                }
+
+                break;
+
             case PInvokeCore.WM_KEYUP:
                 var key = (VIRTUAL_KEY)(uint)m.WParamInternal;
 

src/System.Windows.Forms/System/Windows/Forms/Controls/TreeView/TreeView.cs

@@ -3161,6 +3161,17 @@ protected override unsafe void WndProc(ref Message m)
                     base.WndProc(ref m);
                 }
 
+                break;
+            case PInvokeCore.WM_CTLCOLOREDIT:
+                if (_labelEdit is not null && (HWND)m.LParamInternal == _labelEdit.HWND)
+                {
+                    m.ResultInternal = (LRESULT)(nint)InitializeDCForWmCtlColor((HDC)(nint)m.WParamInternal, m.MsgInternal);
+                }
+                else
+                {
+                    base.WndProc(ref m);
+                }
+
                 break;
             case PInvokeCore.WM_HSCROLL:
                 base.WndProc(ref m);

src/test/unit/System.Windows.Forms/System/Windows/Forms/ListViewTests.cs

@@ -6066,6 +6066,74 @@ public void ListView_GroupTaskLinkClick_EventHandling_ShouldBehaveAsExpected()
         callCount.Should().Be(4);
     }
 
+    [WinFormsTheory]
+    [InlineData(0x1E, 0x1E, 0x1E, 0xFF, 0xFF, 0xFF)]  // Dark mode: dark bg, white text
+    [InlineData(0xFF, 0xFF, 0xFF, 0x00, 0x00, 0x00)]  // Light mode: white bg, black text
+    public void ListView_WmCtlColorEdit_WithMatchingLabelEditHwnd_SetsDCColorsAndReturnsNonZeroBrush(int backR, int backG, int backB, int foreR, int foreG, int foreB)
+    {
+        // Regression test for issue #12042
+        Color expectedBackColor = Color.FromArgb(backR, backG, backB);
+        Color expectedForeColor = Color.FromArgb(foreR, foreG, foreB);
+
+        using SubListView listView = new()
+        {
+            LabelEdit = true,
+            View = View.Details,
+            Size = new Size(300, 200),
+            BackColor = expectedBackColor,
+            ForeColor = expectedForeColor
+        };
+
+        listView.Columns.Add(new ColumnHeader { Text = "Column 1", Width = 200 });
+        listView.Items.Add(new ListViewItem("Item 1"));
+        listView.CreateControl();
+
+        // Select the item then trigger label editing via the timer (same pattern used in
+        // ListView_OnMouseClick_EditLabel_AsExpected).
+        PInvoke.SetFocus(listView);
+        listView.Items[0].Selected = true;
+
+        Point itemLocation = listView.Items[0].Bounds.Location + new Size(1, 1);
+        PInvokeCore.PostMessage(listView, PInvokeCore.WM_LBUTTONUP, 0, PARAM.FromPoint(itemLocation));
+        PInvokeCore.SendMessage(listView, PInvokeCore.WM_LBUTTONDOWN, 1, PARAM.FromPoint(itemLocation));
+        PInvokeCore.SendMessage(listView, PInvokeCore.WM_TIMER,
+            (WPARAM)(nint)listView.TestAccessor.Dynamic.LVLABELEDITTIMER);
+
+        HWND editHwnd = (HWND)(nint)PInvokeCore.SendMessage(listView, PInvoke.LVM_GETEDITCONTROL);
+
+        if (editHwnd == HWND.Null)
+        {
+            PInvokeCore.SendMessage(listView, PInvoke.LVM_CANCELEDITLABEL);
+            return;
+        }
+
+        using GetDcScope hdc = new(editHwnd);
+        Message msg = Message.Create(
+            listView.Handle,
+            (int)PInvokeCore.WM_CTLCOLOREDIT,
+            (nint)(HDC)hdc,
+            (nint)editHwnd);
+
+        listView.WndProc(ref msg);
+
+        // 1. A valid (non-null) brush handle must be returned.
+        Assert.NotEqual(IntPtr.Zero, (nint)msg.ResultInternal);
+
+        // 2. DC text color must match the ForeColor we set on the control.
+        Color actualTextColor = PInvoke.GetTextColor(hdc);
+        Assert.Equal(
+            ColorTranslator.ToWin32(expectedForeColor),
+            ColorTranslator.ToWin32(actualTextColor));
+
+        // 3. DC background color must match the BackColor we set on the control.
+        Color actualBkColor = PInvoke.GetBkColor(hdc);
+        Assert.Equal(
+            ColorTranslator.ToWin32(expectedBackColor),
+            ColorTranslator.ToWin32(actualBkColor));
+
+        PInvokeCore.SendMessage(listView, PInvoke.LVM_CANCELEDITLABEL);
+    }
+
     private class SubListViewItem : ListViewItem
     {
         public AccessibleObject CustomAccessibleObject { get; set; }
@@ -6171,6 +6239,8 @@ private class SubListView : ListView
         public new void OnCacheVirtualItems(CacheVirtualItemsEventArgs e) => base.OnCacheVirtualItems(e);
 
         public new void OnItemChecked(ItemCheckedEventArgs e) => base.OnItemChecked(e);
+
+        public new void WndProc(ref Message m) => base.WndProc(ref m);
     }
 
     private SubListView GetSubListViewWithData(View view, bool virtualMode, bool showGroups, bool withinGroup, bool createControl)

src/test/unit/System.Windows.Forms/System/Windows/Forms/TreeViewTests.cs

@@ -7569,6 +7569,62 @@ public void TreeView_VisibleCount_MultipleNodes_ReturnsExpected(int nodeCount)
         treeView.VisibleCount.Should().Be(5);
     }
 
+    [WinFormsTheory]
+    [InlineData(0x1E, 0x1E, 0x1E, 0xFF, 0xFF, 0xFF)]  // Dark mode: dark bg, white text
+    [InlineData(0xFF, 0xFF, 0xFF, 0x00, 0x00, 0x00)]  // Light mode: white bg, black text
+    public void TreeView_WmCtlColorEdit_WithMatchingLabelEditHwnd_SetsDCColorsAndReturnsNonZeroBrush(int backR, int backG, int backB, int foreR, int foreG, int foreB)
+    {
+        // Regression test for issue #12042
+        Color expectedBackColor = Color.FromArgb(backR, backG, backB);
+        Color expectedForeColor = Color.FromArgb(foreR, foreG, foreB);
+
+        using SubTreeView treeView = new()
+        {
+            LabelEdit = true,
+            Size = new Size(200, 200),
+            BackColor = expectedBackColor,
+            ForeColor = expectedForeColor
+        };
+
+        treeView.Nodes.Add("Node0");
+        treeView.CreateControl();
+
+        treeView.Nodes[0].BeginEdit();
+        HWND editHwnd = (HWND)(nint)PInvokeCore.SendMessage(treeView, PInvoke.TVM_GETEDITCONTROL);
+
+        if (editHwnd == HWND.Null)
+        {
+            treeView.Nodes[0].EndEdit(cancel: true);
+            return;
+        }
+
+        using GetDcScope hdc = new(editHwnd);
+        Message msg = Message.Create(
+            treeView.Handle,
+            (int)PInvokeCore.WM_CTLCOLOREDIT,
+            (nint)(HDC)hdc,
+            (nint)editHwnd);
+
+        treeView.WndProc(ref msg);
+
+        // 1. A valid (non-null) brush handle must be returned.
+        Assert.NotEqual(IntPtr.Zero, (nint)msg.ResultInternal);
+
+        // 2. DC text color must match the ForeColor we set on the control.
+        Color actualTextColor = PInvoke.GetTextColor(hdc);
+        Assert.Equal(
+            ColorTranslator.ToWin32(expectedForeColor),
+            ColorTranslator.ToWin32(actualTextColor));
+
+        // 3. DC background color must match the BackColor we set on the control.
+        Color actualBkColor = PInvoke.GetBkColor(hdc);
+        Assert.Equal(
+            ColorTranslator.ToWin32(expectedBackColor),
+            ColorTranslator.ToWin32(actualBkColor));
+
+        treeView.Nodes[0].EndEdit(cancel: true);
+    }
+
     private class SubTreeView : TreeView
     {
         public new bool CanEnableIme => base.CanEnableIme;
@@ -7674,5 +7730,7 @@ private class SubTreeView : TreeView
         public new void OnNodeMouseHover(TreeNodeMouseHoverEventArgs e) => base.OnNodeMouseHover(e);
 
         public new void OnRightToLeftLayoutChanged(EventArgs e) => base.OnRightToLeftLayoutChanged(e);
+
+        public new void WndProc(ref Message m) => base.WndProc(ref m);
     }
 }