Multi select in SharePoint Web Part Shared Settings?

Im trying to figure out how to create a multi select box in the shared settings section of a SharePoint Web Part. A regular drop down looks l开发者_StackOverflowike this

    public enum SortByEnum { DESC, ASC }; // Set default value first!
    protected SortByEnum sortBy;
    [Category("Some category"),
    WebBrowsable(true),
    Personalizable(PersonalizationScope.Shared),
    WebDisplayName("Sort order"),
    WebDescription("ASC = oldest first, DESC = Newest first")]
    public SortByEnum SortBy
    {
        get { return sortBy; }
        set { sortBy = value; }
    }

Now, anyone who could help me how to make this to a multi select?

You have to implement custom Editor Part and then add MultiSelect ListBox control to it.

See implementing Custom Editor Part:

http://vspug.com/tonstegeman/2007/08/04/creating-custom-editor-parts-for-a-sharepoint-webpart/