public override object EditValue(System.ComponentModel.ITypeDescriptorContext context, System.IServiceProvider provider, object value)
        {
            System.Windows.Forms.Design.IWindowsFormsEditorService service =(System.Windows.Forms.Design.IWindowsFormsEditorService)provider.GetService(typeof(System.Windows.Forms.Design.IWindowsFormsEditorService));
            if (service == null)
            {
                return null;
            }
            PropertyWindow form = new PropertyWindow();
          
form.TableName="这里需要这个自定义控件的其他属性值";

            if (service.ShowDialog(form) == DialogResult.OK)
            {
                return form.SelectedValue;
            }
            return value;
        }

MyControl my = context==null ? null : context.Instance as MyControl;
if(my != null)
{
    form.TableName = my.XXX;
}