dialog service improvements

src/Wpf/Prism.Wpf/Services/Dialogs/DialogService.cs

@@ -74,10 +74,23 @@ public void ShowDialog(string name, IDialogParameters parameters, Action<IDialog
 
         void ShowDialogInternal(string name, IDialogParameters parameters, Action<IDialogResult> callback, bool isModal, string windowName = null)
         {
+            if (parameters == null)
+                parameters = new DialogParameters();
+
             IDialogWindow dialogWindow = CreateDialogWindow(windowName);
             ConfigureDialogWindowEvents(dialogWindow, callback);
             ConfigureDialogWindowContent(name, dialogWindow, parameters);
 
+            ShowDialogWindow(dialogWindow, isModal);
+        }
+
+        /// <summary>
+        /// Shows the dialog window.
+        /// </summary>
+        /// <param name="dialogWindow">The dialog window to show.</param>
+        /// <param name="isModal">If true; dialog is shown as a modal</param>
+        protected virtual void ShowDialogWindow(IDialogWindow dialogWindow, bool isModal)
+        {
             if (isModal)
                 dialogWindow.ShowDialog();
             else

src/Wpf/Prism.Wpf/Services/Dialogs/IDialogServiceExtensions.cs

@@ -0,0 +1,33 @@
+using System;
+
+namespace Prism.Services.Dialogs
+{
+    /// <summary>
+    /// Extensions for the IDialogService
+    /// </summary>
+    public static class IDialogServiceExtensions
+    {
+#if !HAS_WINUI
+        /// <summary>
+        /// Shows a non-modal dialog.
+        /// </summary>
+        /// <param name="dialogService">The DialogService</param>
+        /// <param name="name">The name of the dialog to show.</param>
+        /// <param name="callback">The action to perform when the dialog is closed.</param>
+        public static void Show(this IDialogService dialogService, string name, Action<IDialogResult> callback)
+        {
+            dialogService.Show(name, new DialogParameters(), callback);
+        }
+#endif
+        /// <summary>
+        /// Shows a modal dialog.
+        /// </summary>
+        /// <param name="dialogService">The DialogService</param>
+        /// <param name="name">The name of the dialog to show.</param>
+        /// <param name="callback">The action to perform when the dialog is closed.</param>
+        public static void ShowDialog(this IDialogService dialogService, string name, Action<IDialogResult> callback)
+        {
+            dialogService.ShowDialog(name, new DialogParameters(), callback);
+        }
+    }
+}