Description
📥 Get the project, database scripts, and supporting resources:
👉 https://www.patreon.com/iBasskung/posts/c-net-10-app-171463553
เปิด MDI Child Forms ด้วยวิธีดั้งเดิมด้วย C# .NET 10 WinForms | Visual Studio 2026
C# .NET 10 WinForms Tutorial: Open MDI Child Forms Using the Legacy Approach | Visual Studio 2026
Learn how to open MDI child forms in a C# Windows Forms business application using Visual Studio 2026 and .NET 10.
In this tutorial, you'll learn how to create child forms, connect menu items to form-opening events, configure MDI parent-child relationships, and position child forms within the main application window. You'll also explore the limitations of the traditional approach, including duplicated code, opening duplicate form instances, and common Windows Forms Designer event-handler errors.
🎯 What You'll Learn
- Understand the MDI Parent and MDI Child form architecture
- Create CategoryManagement and ProductManagementForm
- Organize Windows Forms in a View folder
- Open child forms using the traditional `new Form()` approach
- Set the `MdiParent` property to `this`
- Display child forms using `Show()`
- Configure `StartPosition` using `FormStartPosition.Manual`
- Set child form positions using the `Left` and `Top` properties
- Handle menu item Click events to open MDI child forms
- Identify duplicated code when opening multiple child forms
- Understand why the legacy approach can create duplicate form instances
- Troubleshoot Windows Forms Designer errors caused by removed event handlers
- Understand the limitations of the traditional approach before progressing to Generic Methods and Dependency Injection
📌 Lesson Goal
Learn the fundamentals of opening MDI child forms using the traditional approach. This lesson establishes a foundation for the next step: refactoring duplicated form-opening code into a reusable Generic Method, followed by a more modern approach using Dependency Injection.
This tutorial is suitable for beginners learning C# Windows Forms and developers who want to understand traditional MDI application patterns before adopting modern .NET techniques.
🚀 Build a Business Application Step by Step
This lesson is part of the course Build a Business Application with C# and SQL Server using Visual Studio 2026 and Modern .NET.
Follow along to develop a business application step by step, from Windows Forms UI design and application architecture to database integration and business functionality.
Subscribe to iBasskung for more C#, .NET, SQL Server, WinForms, and enterprise application development tutorials.
📦 Want the Complete Project and Learning Resources?
The Business Application course and project package includes source code, three E-Books, and SQL scripts for learning and further development.
Contact iBasskung for more information.
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