<Intersoft:UXPage.Resources>
    <ViewModels:EditorViewModel x:Key="EditorViewModel"></ViewModels:EditorViewModel>
</Intersoft:UXPage.Resources>
<Grid x:Name="LayoutRoot" DataContext="{StaticResource EditorViewModel}">
    <Intersoft:UXDropDownButton Content="File" HorizontalAlignment="Left" Margin="10,10,0,0" Name="uXDropDownButton1" VerticalAlignment="Top">
        <Intersoft:UXMenuItem Header="New" Command="{Binding NewAction}"/>
        <Intersoft:UXMenuItem Header="Save" Command="{Binding SaveAction}"/>
    </Intersoft:UXDropDownButton>
</Grid>

public class EditorViewModel : ViewModelBase
{
    public EditorViewModel()
    {
        this.NewAction = new DelegateCommand(NewCommandAction, CanNewAction);
        this.SaveAction = new DelegateCommand(SaveCommandAction, CanSaveAction);
    }

    public DelegateCommand NewAction { get; private set; }
    public DelegateCommand SaveAction { get; private set; }

    private bool CanNewAction(object parameter)
    {
        //this method validate whether or not the New UXMenuItem is active
        //In this sample, I will keep the New UXMenuItem to be always active
        return true;
    }

    private bool CanSaveAction(object parameter)
    {
        //this method validate whether or not the Save UXMenuItem is active
        //In this sample, I will keep the Save UXMenuItem to be always active
        return true;
    }

    private void NewCommandAction(object parameter)
    {
        //this method will be triggered when the New UXMenuItem is clicked
        MessageBoxServiceProvider.Standalone = true;

        MessageBoxServiceProvider.Show("Execute New Action", "Information",
            Intersoft.Client.UI.Aqua.UXDesktop.MessageBoxButton.OK,
            Intersoft.Client.UI.Aqua.UXDesktop.MessageBoxImage.Information,
            null);
    }

    private void SaveCommandAction(object parameter)
    {
        //this method will be triggered when the Save UXMenuItem is clicked

        MessageBoxServiceProvider.Show("Execute Save Action", "Information",
            Intersoft.Client.UI.Aqua.UXDesktop.MessageBoxButton.OK,
            Intersoft.Client.UI.Aqua.UXDesktop.MessageBoxImage.Information,
            null);
    }
}