Loading and parsing WinForms menus using LINQ
Try this:

public RegexOptions SelectedRegexOptions
{
    get
    {
       RegexOptions options = mnuRegexOptions.MenuItems
            .Cast&lt;MenuItem&gt;()
            .Where(
                x =&gt; x.Checked 
            )
            .Select(s =&gt; (RegexOptions)s.Tag)
            .Aggregate(RegexOptions.None, (x, y) =&gt; x | y);

        return options; 
    }
}


The Aggregate call will take care of the bitwise ORs.