do not crash if we don't have permission to save the file when invoking Save

Libraries/UniversalEditor.UserInterface/MainWindow.cs

@@ -1174,8 +1174,12 @@ namespace UniversalEditor.UserInterface
 		{
 			if (document.IsSaved)
 			{
+				bool inputClosed = false;
 				if (document.InputAccessor != null && document.InputAccessor.IsOpen)
+				{
+					inputClosed = true;
 					document.InputAccessor.Close();
+				}
 
 				if (document.OutputAccessor is FileAccessor)
 				{
@@ -1183,9 +1187,33 @@ namespace UniversalEditor.UserInterface
 					(document.OutputAccessor as FileAccessor).AllowWrite = true;
 					(document.OutputAccessor as FileAccessor).ForceOverwrite = true;
 				}
-				document.OutputAccessor.Open();
-				document.Save();
-				document.OutputAccessor.Close();
+
+				try
+				{
+					document.OutputAccessor.Open();
+					document.Save();
+					document.OutputAccessor.Close();
+				}
+				catch (UnauthorizedAccessException ex)
+				{
+					if (inputClosed)
+					{
+						if (document.InputAccessor is FileAccessor)
+						{
+							// FIXME: ewww
+							(document.InputAccessor as FileAccessor).AllowWrite = false;
+							(document.InputAccessor as FileAccessor).ForceOverwrite = false;
+						}
+						document.InputAccessor.Open();
+					}
+
+					switch (HandleUnauthorizedAccessException(document, ex))
+					{
+						case MultipleDocumentErrorHandling.CancelAll: return false;
+						case MultipleDocumentErrorHandling.CancelOne: return true;
+						case MultipleDocumentErrorHandling.Ignore: break;
+					}
+				}
 
 				DockingWindow di = dckContainer.Items[GetCurrentEditorPage()] as DockingWindow;
 				if (di != null)
@@ -1274,7 +1302,20 @@ namespace UniversalEditor.UserInterface
 				page.Document.DataFormat = df;
 				page.Document.Accessor = accessor;
 			}
-			page.Document.Save();
+
+			try
+			{
+				page.Document.Save();
+			}
+			catch (UnauthorizedAccessException ex)
+			{
+				switch (HandleUnauthorizedAccessException(page.Document, ex))
+				{
+					case MultipleDocumentErrorHandling.CancelAll: return false;
+					case MultipleDocumentErrorHandling.CancelOne: return true;
+					case MultipleDocumentErrorHandling.Ignore: break;
+				}
+			}
 			GetCurrentEditor().Document = page.Document;
 
 			DockingWindow di = dckContainer.Items[page] as DockingWindow;
@@ -1285,6 +1326,25 @@ namespace UniversalEditor.UserInterface
 			}
 			return true;
 		}
+
+		private MultipleDocumentErrorHandling HandleUnauthorizedAccessException(Document document, UnauthorizedAccessException ex)
+		{
+			DialogResult dr = MessageDialog.ShowDialog(String.Format("Cannot save the file in its current location.  Would you like to choose another location?\r\n\r\n{0}", ex.Message), "Unauthorized", MessageDialogButtons.YesNoCancel, MessageDialogIcon.Warning);
+			if (dr == DialogResult.Yes)
+			{
+				SaveFileAs(document);
+			}
+			else if (dr == DialogResult.No)
+			{
+				return MultipleDocumentErrorHandling.CancelOne;
+			}
+			else if (dr == DialogResult.Cancel)
+			{
+				return MultipleDocumentErrorHandling.CancelAll;
+			}
+			return MultipleDocumentErrorHandling.Ignore;
+		}
+
 		public bool SaveFileAs(Accessor accessor, DataFormat df)
 		{
 			return SaveFileAs(accessor, df, GetCurrentEditor()?.ObjectModel);

Libraries/UniversalEditor.UserInterface/MultipleDocumentErrorHandling.cs

@@ -0,0 +1,46 @@
+//
+//  MultipleDocumentErrorHandling.cs
+//
+//  Author:
+//       Michael Becker <alcexhim@gmail.com>
+//
+//  Copyright (c) 2021 Mike Becker's Software
+//
+//  This program is free software: you can redistribute it and/or modify
+//  it under the terms of the GNU General Public License as published by
+//  the Free Software Foundation, either version 3 of the License, or
+//  (at your option) any later version.
+//
+//  This program is distributed in the hope that it will be useful,
+//  but WITHOUT ANY WARRANTY; without even the implied warranty of
+//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+//  GNU General Public License for more details.
+//
+//  You should have received a copy of the GNU General Public License
+//  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+using System;
+namespace UniversalEditor.UserInterface
+{
+	/// <summary>
+	/// Describes the way in which to handle an <see cref="Exception" /> when
+	/// there are additional <see cref="Document" />s to be processed afterward.
+	/// </summary>
+	public enum MultipleDocumentErrorHandling
+	{
+		/// <summary>
+		/// Ignore the error for the current <see cref="Document" /> and proceed
+		/// to processing the next <see cref="Document" />.
+		/// </summary>
+		Ignore,
+		/// <summary>
+		/// Cancels the operation for a single <see cref="Document" />. Other
+		/// <see cref="Document" />s will continue to be processed.
+		/// </summary>
+		CancelOne,
+		/// <summary>
+		/// Cancels the entire operation, including any <see cref="Document" />s
+		/// that still have yet to be processed.
+		/// </summary>
+		CancelAll
+	}
+}

Libraries/UniversalEditor.UserInterface/UniversalEditor.UserInterface.csproj

@@ -136,6 +136,7 @@
     <Compile Include="EditorChangingEvent.cs" />
     <Compile Include="EditorPropertiesPanel.cs" />
     <Compile Include="Editors\FileSystem\FileSystemEditorSettingsGuids.cs" />
+    <Compile Include="MultipleDocumentErrorHandling.cs" />
   </ItemGroup>
   <ItemGroup>
     <BootstrapperPackage Include="Microsoft.Net.Client.3.5">