static void OnIsModifiedChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
TextEditor editor = d as TextEditor;
if (editor != null) {
TextDocument document = editor.Document;
if (document != null) {
UndoStack undoStack = document.UndoStack;
if ((bool)e.NewValue) {
if (undoStack.IsOriginalFile)
undoStack.DiscardOriginalFileMarker();
} else {
undoStack.MarkAsOriginalFile();
}
}
}
}
