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Andy De George
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---
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title: "Walkthrough: Demonstrating Visual Inheritance"
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ms.date: "03/30/2017"
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dev_langs:
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- "csharp"
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- "vb"
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helpviewer_keywords:
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- "form inheritance [Windows Forms], walkthroughs"
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- "visual inheritance"
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- "inheritance [Windows Forms], walkthroughs"
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- "walkthroughs [Windows Forms], visual inheritance"
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- "Windows Forms, inheritance"
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ms.assetid: 01966086-3142-450e-8210-3fd4cb33f591
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---
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# Walkthrough: Demonstrating Visual Inheritance
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Visual inheritance enables you to see the controls on the base form and to add new controls. In this walkthrough you will create a base form and compile it into a class library. You will import this class library into another project and create a new form that inherits from the base form. During this walkthrough, you will learn how to:
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- Create a class library project containing a base form.
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- Add a button with properties that derived classes of the base form can modify.
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- Add a button that cannot be modified by inheritors of the base form.
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- Create a project containing a form that inherits from `BaseForm`.
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Ultimately, this walkthrough will demonstrate the difference between private and protected controls on an inherited form.
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> [!CAUTION]
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> Not all controls support visual inheritance from a base form. The following controls do not support the scenario described in this walkthrough:
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>
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> - <xref:System.Windows.Forms.WebBrowser>
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>
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> - <xref:System.Windows.Forms.ToolStrip>
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>
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> - <xref:System.Windows.Forms.ToolStripPanel>
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>
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> - <xref:System.Windows.Forms.TableLayoutPanel>
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>
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> - <xref:System.Windows.Forms.FlowLayoutPanel>
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>
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> - <xref:System.Windows.Forms.DataGridView>
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>
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> These controls in the inherited form are always read-only regardless of the modifiers you use (`private`, `protected`, or `public`).
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## Create a class library project containing a base form
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1. In Visual Studio, from the **File** menu, choose **New** > **Project** to open the **New Project** dialog box.
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2. Create a Windows Forms application named `BaseFormLibrary`.
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3. To create a class library instead of a standard Windows Forms application, in **Solution Explorer**, right-click the **BaseFormLibrary** project node and then select **Properties**.
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4. In the properties for the project, change the **Output type** from **Windows Application** to **Class Library**.
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5. From the **File** menu, choose **Save All** to save the project and files to the default location.
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The next two procedures add buttons to the base form. To demonstrate visual inheritance, you will give the buttons different access levels by setting their `Modifiers` properties.
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## Add a button that inheritors of the base form can modify
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1. Open **Form1** in the designer.
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2. On the **All Windows Forms** tab of the **Toolbox**, double-click **Button** to add a button to the form. Use the mouse to position and resize the button.
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3. In the Properties window, set the following properties of the button:
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- Set the **Text** property to **Say Hello**.
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- Set the **(Name)** property to **btnProtected**.
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- Set the **Modifiers** property to **Protected**. This makes it possible for forms that inherit from **Form1** to modify the properties of **btnProtected**.
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4. Double-click the **Say Hello** button to add an event handler for the **Click** event.
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5. Add the following line of code to the event handler:
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```vb
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MessageBox.Show("Hello, World!")
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```
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```csharp
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MessageBox.Show("Hello, World!");
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```
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## Add a button that cannot be modified by inheritors of the base form
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1. Switch to design view by clicking the **Form1.vb [Design], Form1.cs [Design], or Form1.jsl [Design]** tab above the code editor, or by pressing F7.
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2. Add a second button and set its properties as follows:
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- Set the **Text** property to **Say Goodbye**.
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- Set the **(Name)** property to **btnPrivate**.
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- Set the **Modifiers** property to **Private**. This makes it impossible for forms that inherit from **Form1** to modify the properties of **btnPrivate**.
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3. Double-click the **Say Goodbye** button to add an event handler for the **Click** event. Place the following line of code in the event procedure:
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```vb
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MessageBox.Show("Goodbye!")
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```
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```csharp
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MessageBox.Show("Goodbye!");
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```
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4. From the **Build** menu, choose **Build BaseForm Library** to build the class library.
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Once the library is built, you can create a new project that inherits from the form you just created.
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## Create a project containing a form that inherits from the base form
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1. From the **File** menu, choose **Add** and then **New Project** to open the **Add New Project** dialog box.
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2. Create a Windows Forms application named `InheritanceTest`.
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## Add an inherited form
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1. In **Solution Explorer**, right-click the **InheritanceTest** project, select **Add**, and then select **New Item**.
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2. In the **Add New Item** dialog box, select the **Windows Forms** category (if you have a list of categories) and then select the **Inherited Form** template.
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3. Leave the default name of `Form2` and then click **Add**.
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4. In the **Inheritance Picker** dialog box, select **Form1** from the **BaseFormLibrary** project as the form to inherit from and click **OK**.
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This creates a form in the **InheritanceTest** project that derives from the form in **BaseFormLibrary**.
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5. Open the inherited form (**Form2**) in the designer by double-clicking it, if it is not already open.
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In the designer, the inherited buttons have a symbol () in their upper corner, indicating they are inherited.
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6. Select the **Say Hello** button and observe the resize handles. Because this button is protected, the inheritors can move it, resize it, change its caption, and make other modifications.
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7. Select the private **Say Goodbye** button, and notice that it does not have resize handles. Additionally, in the **Properties** window, the properties of this button are grayed to indicate they cannot be modified.
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8. If you are using Visual C#:
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1. In **Solution Explorer**, right-click **Form1** in the **InheritanceTest** project and then choose **Delete**. In the message box that appears, click **OK** to confirm the deletion.
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2. Open the Program.cs file and change the line `Application.Run(new Form1());` to `Application.Run(new Form2());`.
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9. In **Solution Explorer**, right-click the **InheritanceTest** project and select **Set As Startup Project**.
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10. In **Solution Explorer**, right-click the **InheritanceTest** project and select **Properties**.
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11. In the **InheritanceTest** property pages, set the **Startup object** to be the inherited form (**Form2**).
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12. Press **F5** to run the application, and observe the behavior of the inherited form.
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## Next steps
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Inheritance for user controls works in much the same way. Open a new class library project and add a user control. Place constituent controls on it and compile the project. Open another new class library project and add a reference to the compiled class library. Also, try adding an inherited control (through the **Add New Items** dialog box) to the project and using the **Inheritance Picker**. Add a user control, and change the `Inherits` (`:` in Visual C#) statement. For more information, see [How to: Inherit Windows Forms](how-to-inherit-windows-forms.md).
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## See also
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- [How to: Inherit Windows Forms](how-to-inherit-windows-forms.md)
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- [Windows Forms Visual Inheritance](windows-forms-visual-inheritance.md)
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- [Windows Forms](../index.yml)
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