Add IsHandleCreated checks before calling SetWindowPos in DesignerFrame

[Copilot]

Fixes #14081

Proposed changes

• Add IsHandleCreated guard in ParentOverlay() before calling SetParent and SetWindowPos
• Add IsHandleCreated check in WndProc WM_PARENTNOTIFY handler before calling SetWindowPos on overlay controls

Customer Impact

• Prevents Visual Studio crashes when custom control properties invoke native window methods during design time
• Accessing Control.Handle without a created handle forces CreateHandle(), which can crash the designer

Regression?

• No

Risk

• Low. Follows existing pattern used throughout WinForms (e.g., Control.BringToFront(), Control.SendToBack())

Test methodology

• Code review passed
• CodeQL security check passed
• Pattern matches existing guards in Control.cs:4406 and Control.cs:10055

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Original prompt

---

This section details on the original issue you should resolve

<issue_title>Visual Studio Crash When Invoking NativeMethods.SetWindowPos Method</issue_title>
<issue_description>## Environment
Visual Studio professional 2026 - version 18.0.0

.NET version

Facing this issue in .NetCore

Did this work in a previous version of Visual Studio and/or previous .NET release?

No

Issue Description

I have a Boolean property named NativeCheck. During the property processing, the SetWindowPos method is invoked. Visual Studio crashes when this method is executed. Below is the method definition:
[DllImport("USER32.dll");
internal static extern bool SetWindowPos(IntPtr hWnd, IntPtr hWndInsertAfter, int X, int Y, int cx, int cy, int uFlags)

Demo Link

CustomControl_Demo.zip

Issue replication video

NativeMethods_Issue.mp4

Steps to reproduce

1. Open the Designer.
2. Select the CustomButton and navigate to the Properties window.
3. Set the NativeCheck property to True.

Expected Behavior: The value should be properly set to the NativeCheck property without any issues.
Observed Behavior: When setting the NativeCheck property to True, Visual Studio crashes.</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Visual Studio Crash When Invoking NativeMethods.SetWindowPos Method #14081

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Microsoft Reviewers: Open in CodeFlow

[codecov]

Codecov Report

❌ Patch coverage is 18.18182% with 9 lines in your changes missing coverage. Please review.
✅ Project coverage is 77.14865%. Comparing base (48f77ea) to head (bfc86fb).

Additional details and impacted files

@@                 Coverage Diff                 @@
##                main      #14086         +/-   ##
===================================================
- Coverage   77.15479%   77.14865%   -0.00615%     
===================================================
  Files           3279        3279                 
  Lines         645317      645323          +6     
  Branches       47718       47720          +2     
===================================================
- Hits          497893      497858         -35     
- Misses        143732      143776         +44     
+ Partials        3692        3689          -3     

Flag	Coverage Δ
Debug	77.14865% <18.18182%> (-0.00615%)	⬇️
integration	18.97114% <18.18182%> (-0.01503%)	⬇️
production	52.00506% <18.18182%> (-0.01325%)	⬇️
test	97.40749% <ø> (ø)
unit	49.44660% <0.00000%> (+0.00417%)	⬆️

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[SimonZhao888]

This is not an issue.