Visual Studio Crashes When Enabling Float or Document Mode on Custom Docked Panel During Design Time in .NET Core Projects

### 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 am using a CustomDockingManager component to dock panels. After docking a panel, I set the EnableFloating property to true to make the panel float. However, Visual Studio crashes or becomes unresponsive during design time in .NET Core projects.
The same issue occurs when I try to set the panel to Document mode—Visual Studio crashes or hangs during design time.

I have attached a sample project (CustomFloatControl.zip) demonstrating the issue.

[CustomFloatcontrol.zip](https://github.com/user-attachments/files/24427527/CustomFloatcontrol.zip)

Kindly provide suggestions to resolve this problem.

### Steps to reproduce

Open the sample project (CustomFloatControl.zip).
Drag and drop the CustomDockingManager component onto the form.
Drag and drop the CustomDockPanel control onto the CustomDockingManager.
Right-click the CustomDockPanel and set EnableDocking = true.
Right-click the CustomDockPanel and set EnableFloating = true.

Expected Behavior: The docked panel should float on the form without issues.
Observed Behavior: Visual Studio crashes or becomes unresponsive during design time.

### Diagnostics

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