PropertyGrid will use default editor for the properties which’s type is enum. This default editor does not allow multiple selections even the Enum has Flags attribute.
I have been prepared a new Editor for this kind of properties. You can download the source codes from here …




Our editor’s code is as follows;

internal class FlagsEditor : UITypeEditor {        FlagsEditorControl editor = null;        public FlagsEditor()        { }        // our editor is a DropDown editor        public override UITypeEditorEditStyle GetEditStyle(ITypeDescriptorContext context)        {              return UITypeEditorEditStyle.DropDown;        }        public override object EditValue(ITypeDescriptorContext context,                                          IServiceProvider provider, object value)        {              // if value is not an enum than we can not edit it              if (!(value is Enum))                     throw new Exception("Value doesn't support");              // try to figure out that is this a Flags enum or not ?              Type enumType = value.GetType();              object[] attributes = enumType.GetCustomAttributes(typeof(FlagsAttribute), true);              if (attributes.Length == 0)                     throw new Exception("Editing enum hasn;t got Flags attribute");              // check the underlying type              Type type = Enum.GetUnderlyingType(value.GetType());              if (type != typeof(byte) && type != typeof(sbyte)                     && type != typeof(short) && type != typeof(ushort)                     && type != typeof(int)&& type != typeof(uint))                     return value;              if (provider != null)              {                     // use windows forms editor service to show drop down                     IWindowsFormsEditorService edSvc = provider.GetService(                                     typeof(IWindowsFormsEditorService))                                   as IWindowsFormsEditorService;                     if (edSvc == null)                            return value;                     if (editor == null)                            editor = new FlagsEditorControl(this);                     // prepare list                     editor.Begin(edSvc, value);                     // show drop down now                     edSvc.DropDownControl(editor);                     // now we take the result                     value = editor.Value;                     // reset editor                     editor.End();              }              return Convert.ChangeType(value, type);        } }

In this code FlagsEditorControl is a UserControl which PropertyGrid hosts it in a drop down during the edit operation.
You can change your design by changing this Control.

To use this editor for a property, we have to write Editor Attribute to that property as the below;

// set editor of this property to our FlagsEditor [Editor(typeof(FlagsEditor), typeof(UITypeEditor))] public FileAttributes FlagsAttribute {        get { return _FlagsAttribute; }        set { _FlagsAttribute = value; } }