[LyX/master] Add a real Cancel button to 'Already Loaded' dialog box (part of #8787). Also correlate the other buttons more explicitly to the question asked.

[Juergen Spitzmueller]

commit afab1140e9598b136e7deb89d79275087c422ca4
Author: Juergen Spitzmueller <sp...@lyx.org>
Date:   Thu Nov 28 17:06:49 2013 +0100

    Add a real Cancel button to 'Already Loaded' dialog box (part of #8787).
    Also correlate the other buttons more explicitly to the question asked.

diff --git a/src/buffer_funcs.cpp b/src/buffer_funcs.cpp
index d096eeb..26bff55 100644
--- a/src/buffer_funcs.cpp
+++ b/src/buffer_funcs.cpp
@@ -73,13 +73,22 @@ Buffer * checkAndLoadLyXFile(FileName const & filename, 
bool const acceptDirty)
                docstring const text = bformat(_(
                                "The document %1$s is already loaded and has 
unsaved changes.\n"
                                "Do you want to abandon your changes and reload 
the version on disk?"), file);
-               if (!Alert::prompt(_("Reload saved document?"),
-                         text, 1, 1,  _("&Reload"), _("&Keep Changes"))) {
-                       // reload the document
-                       if (checkBuffer->reload() != Buffer::ReadSuccess)
+               int res = Alert::prompt(_("Reload saved document?"),
+                                       text, 2, 2,  _("Yes, &Reload"), _("No, 
&Keep Changes"), _("&Cancel"));
+               switch (res) {
+                       case 0: {
+                               // reload the document
+                               if (checkBuffer->reload() != 
Buffer::ReadSuccess)
+                                       return 0;
+                               return checkBuffer;
+                       }
+                       case 1:
+                               // keep changes
+                               return checkBuffer;
+                       case 2:
+                               // cancel
                                return 0;
                }
-               return checkBuffer;
        }
 
        bool const exists = filename.exists();