Message box

To show a message box start by registering the view by decorating the XAML with the attached property DialogServiceViews.IsRegistered.

<UserControl
  x:Class="DemoApplication.Features.MessageBox.Views.MessageBoxTabContent"
  xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
  xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
  xmlns:md="https://github.com/fantasticfiasco/mvvm-dialogs"
  md:DialogServiceViews.IsRegistered="True">

</UserControl>

In the view model, open the dialog by calling IDialogService.ShowMessageBox.

public class MessageBoxTabContentViewModel : INotifyPropertyChanged
{
  private readonly IDialogService dialogService;
  
  public MessageBoxTabContentViewModel(IDialogService dialogService)
  {
    this.dialogService = dialogService;
  }
  
  private void ShowMessageBox()
  {
    dialogService.ShowMessageBox(
      this,
      "This is the text.",
      "This Is The Caption",
      MessageBoxButton.OKCancel,
      MessageBoxImage.Information);
  }
}