It's not tricky to replace the standard Error dialog. Simply set following property in your application.xml or web.xml.

<Application.Error.classname>com.demo.apps.MyError</Application.Error.classname>

Your own implementation should look like following class:

MyError.java

import com.sibvisions.rad.application.Error;
import javax.rad.ui.container.IDesktopPanel;
 
public class MyError extends Error
{
    public MyError(IDesktopPanel pDesktop) throws Exception
    {
        super(pDesktop);
 
        //hide the details button
        getDetailsButton().setVisible(false);
    }
}

Our custom error dialog hides the Details button.

If you want to replace the error dialog with your own error handling, read this article.