inheritance generic form cannot be shown in designer

Question

I meet a problem today. As following.
I create a generic Form ,
public class Form1:Form
Then I create another inheritance form,
public class From2:Form1.

Answer 1

I had like to give a more concrete answer on as addition to the post of Adam.

BaseForm is the name of your generic form, GenericClass one of the possible type parameters.

BaseForm<T> could look like this:

public class BaseForm<T> : Form
{ }

First, you need the above base class. In fact this is the part you'd probably already used before bumping into this question.

Then you use this intermediate implementation.

public class SampleFormIntermediate : BaseForm<GenericClass>
{
    public SampleFormIntermediate()
    {
        InitializeComponent();
    }
}

And you need to use this class for the Visual Studio designer. And only that. I would recommend to decorate this with a compiler directive so it only gets used in Debug mode:

public partial class SampleForm : SampleFormIntermediate
{
}

Using this Visual Studio 'understands' what to open in the designer and how to open it.

Answer 2

This is a limitation with the designer. You can work around it by adding an interim derived form that specifies the types. I've explained this in a blog post:

http://adamhouldsworth.blogspot.com/2010/02/winforms-visual-inheritance-limitations.html