ReadOnly properties with ExpandableObjectConverter TypeConverter do not display as ReadOnly in PropertyGird

The ExpandableObjectConverter is used in conjunction with the PropertyGrid to provide custom editing capabilities for complex property types. However, when you use the ExpandableObjectConverter with a ReadOnly property, it might not correctly display as read-only in the PropertyGrid. This behavior can be due to limitations in the PropertyGrid control itself.

To work around this issue and make a read-only property appear as read-only in the PropertyGrid, you can create a custom TypeConverter that inherits from ExpandableObjectConverter. In the custom TypeConverter, you can override the GetProperties method and return a collection of properties that are all read-only.

Here's an example of how you might achieve this in C#:

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using System;

using System.ComponentModel;

using System.Reflection;



public class ReadOnlyPropertyConverter : ExpandableObjectConverter

{

    public override PropertyDescriptorCollection GetProperties(ITypeDescriptorContext context, object value, Attribute[] attributes)

    {

        PropertyDescriptorCollection originalProperties = base.GetProperties(context, value, attributes);



        // Create a new collection to hold read-only properties

        PropertyDescriptorCollection readOnlyProperties = new PropertyDescriptorCollection(null);



        // Add only read-only properties to the new collection

        foreach (PropertyDescriptor property in originalProperties)

        {

            if (property.IsReadOnly)

            {

                readOnlyProperties.Add(new ReadOnlyPropertyDescriptor(property));

            }

        }



        return readOnlyProperties;

    }

}



public class ReadOnlyPropertyDescriptor : PropertyDescriptor

{

    private PropertyDescriptor innerPropertyDescriptor;



    public ReadOnlyPropertyDescriptor(PropertyDescriptor innerPropertyDescriptor)

        : base(innerPropertyDescriptor)

    {

        this.innerPropertyDescriptor = innerPropertyDescriptor;

    }



    public override bool IsReadOnly

    {

        get { return true; }

    }



    // Other PropertyDescriptor methods...

}

Then, apply the ReadOnlyPropertyConverter to the property that you want to appear as read-only:

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[TypeConverter(typeof(ReadOnlyPropertyConverter))]

public YourComplexType YourReadOnlyProperty { get; set; }

By creating a custom TypeConverter and using a ReadOnlyPropertyDescriptor, you ensure that the read-only properties within your ExpandableObjectConverter-managed properties are correctly displayed as read-only in the PropertyGrid.