Question

public class MyClass
{
    // Some staff
}

public class MyControl : UserControl
{
    public MyClass MyObj { get; set; }
}

I want MyObj property to be able to set through the property window of MS Visual Studio. However it is grayed like a readonly property.

I suppose that I should add some designer attributes, but have no idea where and which.

Edit

The simplest solution is to inherit MyClass from Component. No attributes are required.

public class MyClass : Component

Answer 1

Try if this works

[TypeConverter(typeof(ExpandableObjectConverter))]
public class MyClass
{
    // Some staff
}


public class MyControl : UserControl
{
    [DesignerSerializationVisibilityAttribute(DesignerSerializationVisibility.Content)]     
    public MyClass MyObj { get; set; }
}

EDITED after user comment:
This test code works as expected to me:

public partial class MyControl : UserControl
{
    public MyControl()
    {
        InitializeComponent();
        MyObj = new MyClass();

    }
    [DesignerSerializationVisibilityAttribute(DesignerSerializationVisibility.Content)]     
    public MyClass MyObj { get; set; }
}


[TypeConverter(typeof(ExpandableObjectConverter))]
public class MyClass
{
    public string Test { get; set; }
}

EDITED AGAIN:
If you want property editor to behave like you describe, the simplest solution I can give you is this

public class MyClass : Control // if it must be visible on form

or

public class MyClass : Component // if it must be just a component